Composite materials for cookware

ABSTRACT

Composite materials for cooking apparatuses which are produced by applying, to a substrate, a material comprising a fluorine-containing polymer having an excellent adhesive property to the substrate without necessitating complicated steps and are excellent in heat resistance, non-sticking property, stain-proofing property, water- and oil-repelling property, stain-removing property, chemical resistance, rust-preventing property, antibacterial property, resistance to energy ray and abrasion resistance. The composite materials for cooking apparatuses are produced by applying, to the substrate, the material comprising a fluorine-containing ethylenic polymer having functional group which is prepared by copolymerizing (a) 0.05 to 30 % by mole of at least one of fluorine-containing ethylenic monomers having at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester group and epoxy, and (b) 70 to 99.95 % by mole of at least one of fluorine-containing ethylenic monomers having no functional group mentioned above.

[0001] The present invention relates to composite materials for cookingapparatuses which are produced by applying, to a substrate, afluorine-containing polymer excellent in heat resistance, non-stickingproperty, transparency (property for exhibiting clear surface pattern),stain-proofing property and water- and oil-repelling property andparticularly in adhesive property to the substrate.

PRIOR ART

[0002] With respect to cooking apparatuses represented by a griddle anda rice cooker, it is desired that cooking can be done at highertemperature for shortening of cooking time and to pursue good taste ofcooked dishes. Also it is desired that stains such as oil and scorch canbe easily removed so as to make cleaning of these apparatuses easy afterthe cooking. Further good property for exhibiting clear surface patternis also desired from the viewpoint of appearance thereof.

[0003] In order to meet such requirements, for the composite materialsused for cooking apparatuses (cooking appliances, wares, utensils,tools, etc.), a fluorine-containing resin which is excellent in heatresistance, chemical resistance, weather resistance, surface properties(friction resistance, etc.), electric insulating property and the likeis used in the form of coating or film.

[0004] However the fluorine-containing resin involves a substantialproblem, namely insufficient adhesion to a metal or glass substrate dueto its excellent non-sticking property.

[0005] Therefore in case where the fluorine-containing resin is used inthe form of coating, there is a method of adhering a fluorine-containingresin to a substrate by roughening the surface of metal chemically orphysically with expecting anchor effect between them. However thismethod requires much labor in the surface roughening itself, and thoughinitial adhesion is possible, lowering of the anchor effect arises whena temperature change is made repeatedly and in case of use at hightemperature.

[0006] Also a method for chemically activating a surface of afluorine-containing resin by treating the surface with a solutionprepared by dissolving metallic sodium in liquid ammonia has beenproposed. However in that method, not only there is a fear that thesolution itself causes environmental pollution but also there is aproblem that its handling is attended with danger.

[0007] Further though a method for carrying out physical and chemicaltreatment such as plasma sputtering on a surface of afluorine-containing resin has been proposed, there is a problem thatmuch labor is required for the treatment and an increase in cost isresulted.

[0008] Also in order to improve adhesion of a fluorine-containing resincoating composition, investigations with respect to addition of variouscomponents and use of a primer have been made.

[0009] For example, there is a technique of adding an inorganic acidsuch as chromic acid to a coating composition containing afluorine-containing resin to form chemical conversion coating film on asurface of metal for enhancing adhesion of the composition(JP-B-63-2675). However since chromic acid contains hexahydric chromium,it cannot be said that such a technique is sufficient in view of safetyin food and coating work. Further in case of use of other inorganicacids such as phosphoric acid, there was a problem that safety of afluorine-containing resin coating composition is damaged.

[0010] Use of a coating composition containing a fluorine-containingresin as a primer, in which heat resistant resins such aspolyamideimide, polyimide, polyethersulfone and polyether ether ketoneand in addition, a metal powder are added instead of the above-mentionedinorganic acid, has been studied (JP-A-6-264000). Inherently there isalmost no compatibility between a fluorine-containing resin and a heatresistant resin. Therefore there arises a phase separation in a coatingfilm, thus easily causing intercoat adhesion failure between the primerand the top coat of the fluorine-containing resin. Further film defectssuch as pin holes and cracks arise easily at the time of processing athigh temperature or during use due to a difference in heat shrinkagebetween the fluorine-containing resin and the heat resistant resin ordue to lowering of elongation of the coating film by the addition of theheat resistant resin. Also since those heat resistant resins are coloredbrown by baking, property for exhibiting clear surface pattern is poorand it is difficult to use them for applications requiring white andvivid colors and transparency. Further when the heat resistant resin isblended, non-sticking property and friction resistance which thefluorine-containing resin possesses inherently are lowered.

[0011] Also for adhesion of a fluorine-containing resin coatingcomposition to glass, etc. requiring transparency, an improvement of theadhesion has been tried by treating the substrate with a silane couplingagent or adding a silicone resin to the fluorine-containing resincoating composition (JP-B-54-42366, JP-A-5-177768). However enhancementof adhesion is insufficient, heat resistance is lowered and separationof film, foaming and coloring arise easily at sintering or in use athigh temperature.

[0012] On the contrary, fluorine-containing resin coating compositionsprepared by copolymerizing a hydrocarbon monomer (containing nofluorine) containing functional group such as hydroxyl or carboxyl havebeen discussed. However those coating compositions were originallystudied mainly for a purpose of weather resistance, and it is difficultto use them for application requiring heat resistance at 200° to 350° C.which is directed by the present invention, and for applicationsrequiring non-sticking property, friction resistance, etc.

[0013] Namely with respect to a polymer prepared by copolymerizing ahydrocarbon monomer (containing no fluorine) having functional group,thermal decomposition easily occurs on components of the monomer at thetime of processing at high temperature or during use, and thus coatingfilm failure, coloring, foaming, separation, etc. arise, which makes itimpossible to attain purposes of coating a fluorine-containing resin.

[0014] Further fluorine-containing resins are generally insufficient inmechanical strength and dimensional stability, and high in price. Inorder to make the best use of the above-mentioned merits of thefluorine-containing polymer and minimize its disadvantages,investigations have been made also with respect to its use in the formof film.

[0015] However the fluorine-containing resin inherently has low adhesiveforce, and it is difficult to adhere the fluorine-containing resindirectly to other material (substrate). For example, even if theadhering is tried by thermo-processing, adhesive strength of thefluorine-containing resin is not enough, or even if the resin hasadhesive force to a certain extent, such an adhesive force is apt tovary depending on kind of the substrate. Thus in many cases, reliabilityon the adhesive strength of the fluorine-containing resin has been notso enough.

[0016] In order to adhere the fluorine-containing resin film to asubstrate, mainly the following methods have been studied:

[0017] 1. a method for physically roughening a surface of substrate bysand blasting, etc.,

[0018] 2. a method for surface-treating a fluorine-containing resin filmby chemical treatment such as sodium etching, plasma treatment,photochemical treatment, etc.,

[0019] 3. a method for adhering by using an adhesive, and other methods.With respect to the methods 1 and 2 above, surface-treating steps arerequired, and the steps are complicated and productivity is poor. Alsokinds and shapes of substrates are restricted. The fluorine-containingresin film inherently has low adhesive force, and there easily occurproblems with appearance such as coloring and color (property forexhibiting clear surface pattern) of the obtained composite material.Also the method of using a chemical such as sodium etching has a problemwith safety.

[0020] Use of an adhesive in the method 3 above has also been discussed.A usual hydrocarbon type (non-fluorine-containing) adhesive does nothave enough adhesive property and its heat resistance is insufficient.Thus a hydrocarbon type adhesive cannot stand under conditions foradhering of a fluorine-containing polymer film, which requires moldingand processing at high temperature, and peeling due to decomposition ofthe adhesive and coloring occur. The above-mentioned laminated articleproduced by using an adhesive also lacks in reliability with respect toits adhesive property, since an adhesive layer is insufficient in heatresistance, chemical resistance and water resistance and its adhesiveforce cannot be maintained due to a change in temperature andenvironment.

[0021] On the contrary, adhesion by using an adhesive and adhesivecomposition comprising a fluorine-containing polymer having functionalgroup is discussed.

[0022] For example, it is reported that a fluorine-containing polymerprepared by graft-polymerizing, to the fluorine-containing polymer, ahydrocarbon monomer which has carboxyl represented by maleic anhydrideand vinyltrimethoxysilane, a residual group of carbonic acid, epoxy or ahydrolyzable silyl group, is used as an adhesive (for example,JP-A-7-18035, JP-A-7-25952, JP-A-7-25954, JP-A-7-173230, JP-A-7-173446,JP-A-7-173447) and that an adhesive composition comprising afluorine-containing copolymer prepared by copolymerizing a hydrocarbonmonomer having functional group such as hydroxyalkyl vinyl ether withtetrafluoroethylene or chlorotrifluoroethylene and an isocyanatehardening agent is cured and used as an adhesive between vinyl chlorideand corona-discharged ETFE (for example, JP-A-7-228848).

[0023] The above-mentioned adhesive or adhesive composition comprising afluorine-containing resin prepared by graft-polymerizing orcopolymerizing a hydrocarbon monomer having functional group does nothave enough heat resistance, and thus at the time of processing acomposite material comprising the adhesive or adhesive composition and afluorine-containing resin film at high temperature or during use at hightemperature, decomposition and foaming occur, thereby causing reductionof adhesive strength, peeling and coloring. In case of the adhesivecomposition disclosed in JP-A-7-228848, it is necessary tocorona-discharge the fluorine-containing resin film.

[0024] As mentioned above, there have been no material for compositematerials for cooking apparatuses which meets the above-mentionedrequirements and assures strong adhesion to a substrate and excellentproperty for exhibiting clear surface pattern.

[0025] In view of the above-mentioned facts, an object of the presentinvention is to provide composite materials for cooking apparatuseswhich are produced by applying, to a substrate, a material comprising afluorine-containing polymer being excellent in adhesion to the substratewithout necessitating complicated steps.

[0026] Further an object of the present invention is to providecomposite materials for cooking apparatuses which are excellent innon-sticking property, stain-proofing property, water- and oil-repellingproperty, stain removing property, chemical resistance, rust preventingproperty, antibacterial property, resistance to energy ray and frictionresistance.

DISCLOSURE OF THE INVENTION

[0027] The present invention relates to composite materials for cookingapparatuses which are produced by applying, to a substrate, a materialcomprising a fluorine-containing ethylenic polymer having functionalgroup and prepared by copolymerizing:

[0028] (a) 0.05 to 30% by mole of at least one of fluorine-containingethylenic monomers having at least one functional group selected fromthe group consisting of hydroxyl, carboxyl, a carboxylic salt group, acarboxylic ester group and epoxy and

[0029] (b) 70 to 99.95% by mole of at least one of fluorine-containingethylenic monomers having no functional group mentioned above.

[0030] In that case, it is preferable that the above-mentionedfluorine-containing ethylenic monomer (a) having functional group is atleast one of fluorine-containing ethylenic monomers represented by theformula (1):

CX₂═CX¹—R_(f)—Y  (1)

[0031] wherein Y is —CH₂OH, —COOH, a carboxylic salt group, a carboxylicester group or epoxy, X and X¹ are the same or different and each ishydrogen atom or fluorine atom, R_(f) is a divalent alkylene grouphaving 1 to 40 carbon atoms, a fluorine-containing oxyalkylene grouphaving 1 to 40 carbon atoms, a fluorine-containing alkylene group havingether bond and 1 to 40 carbon atoms or a fluorine-containing oxyalkylenegroup having ether bond and 1 to 40 carbon atoms.

[0032] Further it is preferable that the above-mentionedfluorine-containing ethylenic monomer (b) having no functional group istetrafluoroethylene.

[0033] Further it is preferable that the above-mentionedfluorine-containing ethylenic monomer (b) having no functional group isa monomer mixture of 85 to 99.7% by mole of tetrafluoroethylene and 0.3to 15 % by mole of a monomer represented by the formula (2):

CF₂═CF—R_(f) ¹  (2)

[0034] wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² is aperfluoroalkyl group having 1 to 5 carbon atoms.

[0035] Further it is preferable that the above-mentionedfluorine-containing ethylenic monomer (b) having no functional group isa monomer mixture comprising 40 to 80% by mole of tetrafluoroethylene,20 to 60% by mole of ethylene and 0 to 15% by mole of other monomercopolymerizable with those monomers.

[0036] Also the present invention relates to the composite materials forcooking apparatuses, which are produced by applying, to a substrate, theabove-mentioned fluorine-containing ethylenic polymer having functionalgroup in the form of coating.

[0037] Also the present invention relates to the composite materials forcooking apparatuses, which are produced by applying, to a substrate, theabove-mentioned fluorine-containing ethylenic polymer having functionalgroup in the form of an aqueous dispersion.

[0038] Also the present invention relates to the composite materials forcooking apparatuses, which are produced by applying, to a substrate, theabove-mentioned fluorine-containing ethylenic polymer having functionalgroup in the form of a powder coating composition.

[0039] Also the present invention relates to the composite materials forcooking apparatuses, which are produced by applying, to a substrate, theabove-mentioned fluorine-containing ethylenic polymer having functionalgroup in the form of a film.

[0040] It is preferable that the above-mentioned substrate is a metallicsubstrate.

[0041] Also it is preferable that the above-mentioned substrate is aglass substrate.

[0042] The present invention relates to cooking apparatuses produced byusing the composite materials for cooking apparatuses.

[0043] Also the present invention relates to heating apparatuses forcooking produced by using the composite materials for cookingapparatuses.

[0044] Also the present invention relates to a griddle produced by usingthe composite materials for cooking apparatuses.

[0045] Also the present invention relates to a griddle produced by usingthe composite materials for cooking apparatuses on its heating surfacemade of metal.

[0046] Also the present invention relates to a griddle produced by usingthe composite materials for cooking apparatuses on its glass lid.

[0047] Also the present invention relates to a range with oven producedby using the composite materials for cooking apparatuses.

[0048] Also the present invention relates to a range with oven producedby using the composite materials for cooking apparatuses on its innersurface made of metal.

[0049] Also the present invention relates to a range with oven producedby using the composite materials for cooking apparatuses on its cookingplate.

[0050] Also the present invention relates to a range with oven producedby using the composite materials for cooking apparatuses on its glassdoor.

[0051] Also the present invention relates to a heating pot produced byusing the composite materials for cooking apparatuses.

[0052] Also the present invention relates to a heating pot produced byusing the composite materials for cooking apparatuses on its heatingsurface made of metal.

[0053] Also the present invention relates to a heating pot produced byusing the composite materials for cooking apparatuses on its glass lid.

[0054] Also the present invention relates to a frying pan produced byusing the composite materials for cooking apparatuses.

[0055] Also the present invention relates to a frying pan produced byusing the composite materials for cooking apparatuses on its heatingsurface made of metal.

[0056] Also the present invention relates to a fryer produced by usingthe composite materials for cooking apparatuses.

[0057] Also the present invention relates to a fryer produced by usingthe composite materials for cooking apparatuses on its inner surfacemade of metal.

[0058] Also the present invention relates to a fryer produced by usingthe composite materials for cooking apparatuses on its inner surfacemade of glass.

[0059] Also the present invention relates to a rice cooker produced byusing the composite materials for cooking apparatuses.

[0060] Also the present invention relates to a rice cooker produced byusing the composite materials for cooking apparatuses on its innersurface made of metal.

[0061] Also the present invention relates to a rice cooker produced byusing the composite materials for cooking apparatuses on its inner lidmade of metal.

[0062] Also the present invention relates to a pot produced by using thecomposite materials for cooking apparatuses.

[0063] Also the present invention relates to a pot produced by using thecomposite materials for cooking apparatuses on its inner surface made ofmetal.

[0064] Also the present invention relates to a pot produced by using thecomposite materials for cooking apparatuses on its inner lid made ofmetal.

[0065] Also the present invention relates to a tableware or vesselproduced by using the composite materials for cooking apparatuses.

[0066] Also the present invention relates to a metallic tableware orvessel produced by using the composite materials for cookingapparatuses.

[0067] Also the present invention relates to a glass tableware or vesselproduced by using the composite materials for cooking apparatuses.

[0068] Also the present invention relates to cooking apparatuses forprocessing foods which are produced by using the composite materials forcooking apparatuses.

[0069] Also the present invention relates to cooking apparatuses formixing foods which are produced by using the composite materials forcooking apparatuses.

[0070] Also the present invention relates to cooking apparatuses forcutting foods which are produced by using the composite materials forcooking apparatuses.

[0071] Also the present invention relates to baking apparatuses producedby using the composite materials for cooking apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS

[0072]FIG. 1 is a diagrammatic plan view of an adhered sample made tomeasure adhesive strength in Example 7 of the present invention.

[0073]FIG. 2 is a diagrammatic perspective view of a test sample used tomeasure adhesive strength in Example 7 of the present invention.

[0074]FIG. 3 is a diagrammatic perspective view of a laminated articlemade to produce a test piece to be subjected to adhesion test (T-typepeeling test) in the present invention.

[0075]FIG. 4 is a diagrammatic perspective view of a test piece to besubjected to adhesion test (T-type peeling test) in the presentinvention.

[0076]FIG. 5 is a diagrammatic perspective view of a test piece to besubjected to adhesion test (tensile shear strength test) in the presentinvention.

[0077]FIG. 6 is a diagrammatic view of a test device to be used foradhesion test (tensile shear strength test) in the present invention.

[0078]FIG. 7 is a diagrammatic cross-sectional view of a laminated testplate made in Example 15 of the present invention.

[0079]FIG. 8 is a diagrammatic cross-sectional view of a three-layeredlaminated article made in Example 15 of the present invention.

[0080]FIG. 9 is a diagrammatic cross-sectional view of a laminatedarticle made in Comparative Example 10 of the present invention.

[0081]FIG. 10 is a diagrammatic cross-sectional view of a laminated testplate for making a laminated article in Example 16 of the presentinvention.

[0082]FIG. 11 is a diagrammatic cross-sectional view of a laminatedarticle made in Example 16 of the present invention.

[0083]FIG. 12 is a diagrammatic cross-sectional view of a laminatedarticle to be subjected to T-type peeling test in Example 16 of thepresent invention.

[0084]FIG. 13 is a diagrammatic cross-sectional view of a laminatedarticle to be subjected to T-type peeling test in Comparative Example 10of the present invention.

[0085]FIG. 14 is a diagrammatic cross-sectional view of a laminated testplate made in Comparative Example 12 of the present invention.

[0086]FIG. 15 is a diagrammatic perspective view of a test piece to besubjected to non-stickiness test in Example of the present invention.

[0087]FIG. 16 is a diagrammatic perspective view of an aluminum platehaving a coating film and obtained in (1) of Example 19 of the presentinvention

[0088]FIG. 17 is a diagrammatic perspective view of a test sample formeasuring adhesive strength in (2) of Example 19 of the presentinvention.

[0089]FIG. 18 is a diagrammatic cross-sectional view of a laminated testplate made in Example 22.

[0090]FIG. 19 is a diagrammatic cross-sectional view of a three-layeredlaminated article made in Example 22 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0091] The composite material for cooking apparatuses of the presentinvention is one produced by applying, to a substrate, a materialcomprising a fluorine-containing ethylenic polymer having functionalgroup and prepared by copolymerizing:

[0092] (a) 0.05 to 30% by mole of at least one of fluorine-containingethylenic monomers having at least one functional group selected fromthe group consisting of hydroxyl, carboxyl, a carboxylic salt group, acarboxylic ester group and epoxy and

[0093] (b) 70 to 99.95% by mole of at least one of fluorine-containingethylenic monomers having no functional group mentioned above.

[0094] The above-mentioned material comprising a fluorine-containingethylenic polymer having functional group has surprisingly strongadhesive property in the form of coating or film to metal, glass andother substrates even without use of an adhesive, surface-treatment onthe substrate, formation of a primer layer and addition of a componenthaving adhesive property in the material.

[0095] With respect to the fluorine-containing ethylenic polymer havingfunctional group which is used for preparing the composite material ofthe present invention, it is important to copolymerize (a) theabove-mentioned fluorine-containing ethylenic monomer having functionalgroup and (b) the fluorine-containing ethylenic monomers having nofunctional group mentioned above to introduce the functional group intothe fluorine-containing polymer, thereby making it possible to giveexcellent adhesive force directly to surfaces of various substrates, towhich adhesion has been difficult or impossible. Namely as compared witha fluorine-containing polymer prepared by copolymerizing anon-fluorine-containing monomer having functional group, thefluorine-containing polymer of the present invention is excellent inheat resistance, and decomposition at processing at high temperature(for example, 200° to 400° C.) can be inhibited more and a largeadhesive strength can be obtained. Further a coating layer being freefrom coloring, foaming, pin hole caused thereby and leveling failure canbe formed on a substrate. Also in case where the composite material isused at high temperature, adhesive property is maintained and a coatinglayer failure such as coloring, whitening, foaming or pin hole isdifficult to arise.

[0096] The above-mentioned fluorine-containing polymer having functionalgroup has excellent characteristics such as not only heat resistancethereof but also chemical resistance, non-sticking property,stain-proofing property, friction resistance and weather resistance of afluorine-containing polymer and can give such excellent characteristicsto a composite material without lowering them.

[0097] Then the fluorine-containing ethylenic copolymer havingfunctional group which is a material for the composite material of thepresent invention is explained below.

[0098] The functional group of the fluorine-containing ethylenic polymerhaving functional group is at least one functional group selected fromthe group consisting of hydroxyl, carboxyl, a carboxylic salt group, acarboxylic ester group and epoxy, and provides the polymer with adhesionto various substrates by its effect. Kinds and combination of thefunctional groups are optionally selected depending on kind of a surfaceof the substrate and purpose and application. From the viewpoint of heatresistance, hydroxyl is most preferable.

[0099] Examples of the preferred fluorine-containing ethylenic monomer(a) having functional group which is one of components constituting thefluorine-containing ethylenic polymer having functional group arefluorine-containing ethylenic monomers (a-1) having functional groupwhich are represented by the formula (1):

CX₂═CX¹—R_(f)—Y  (1)

[0100] wherein Y is —CH₂OH, —COOH, a carboxylic salt group, a carboxylicester group or epoxy, X and X¹ are the same or different and each ishydrogen atom or fluorine atom, R_(f) is a divalent alkylene grouphaving 1 to 40 carbon atoms, a fluorine-containing oxyalkylene grouphaving 1 to 40 carbon atoms, a fluorine-containing alkylene group havingether bond and 1 to 40 carbon atoms or a fluorine-containing oxyalkylenegroup having ether bond and 1 to 40 carbon atoms.

[0101] Examples of the fluorine-containing ethylenic monomer (a-1)having functional group are one represented by the formula (3):

CF₂═CF—R_(f)—Y  (3)

[0102] wherein Y is as defined in the above formula (1), R_(f) ³ is adivalent fluorine-containing alkylene group having 1 to 40 carbon atomsor OR_(f) ⁴, in which R_(f) ⁴ is a divalent fluorine-containing alkylenegroup having 1 to 40 carbon atoms or a divalent fluorine-containingalkylene group having ether bond and 1 to 40 carbon atoms, onerepresented by the formula (4):

CF₂═CFCF₂—OR_(f) ⁵—Y  (4)

[0103] wherein Y is as defined in the above formula (1), R_(f) ⁵ is adivalent fluorine-containing alkylene group having 1 to 39 carbon atomsor a divalent fluorine-containing alkylene group having ether bond and 1to 39 carbon atoms, one represented by the formula (5):

CH₂═CFCF₂—R_(f) ⁵—Y  (5)

[0104] wherein Y is as defined in the above formula (1), R_(f) ⁶ is adivalent fluorine-containing alkylene group having 1 to 39 carbon atomsor OR_(f) ⁷, in which R_(f) ⁷ is divalent fluorine-containing alkylenegroup having 1 to 39 carbon atoms or a divalent fluorine-containingalkylene group having ether bond and 1 to 39 carbon atoms, onerepresented by the formula (6):

CH₂═CH—R_(f) ⁸ 13 Y  (6)

[0105] wherein Y is as defined in the above formula (1), R_(f) ⁸ is adivalent fluorine-containing alkylene group having 1 to 40 carbon atoms,or the like monomer.

[0106] From the viewpoint that copolymerizability with thefluorine-containing ethylenic monomer (b) having no functional group iscomparatively good and that heat resistance of the obtained polymer isnot lowered remarkably, the fluorine-containing ethylenic monomershaving functional group and represented by the formulae (3) to (6) arepreferable.

[0107] Among them, from the viewpoint of copolymerizability with thefluorine-containing ethylenic monomer (b) having no functional group andheat resistance of the obtained polymer, the compounds of the formulae(3) and (5) are preferable, and the compound of the formula (5) isparticularly preferable.

[0108] Examples of the fluorine-containing ethylenic monomer havingfunctional group and represented by the formula (3) are:

CF₂═CFOCF₂CF₂CH₂OH, CF₂═CFO(CF₂)₃COOH,

CF₂═CFOCF₂CF₂COOCH₃,

 CF₂═CFCF₂COOH, CF₂═CFCF₂CH₂OH,

[0109] and the like.

[0110] Examples of the fluorine-containing ethylenic monomer havingfunctional group and represented by the formula (4) are:

CF₂═CFCF₂OCF₂CF₂CF₂COOH,

[0111] and the like.

[0112] Examples of the fluorine-containing ethylenic monomer havingfunctional group and represented by the formula (5) are:

CH₂═CFCF₂CF₂CH₂CH₂OH, CH₂═CFCF₂CF₂COOH,

[0113] and the like.

[0114] Examples of the fluorine-containing ethylenic monomer havingfunctional group and represented by the formula (6) are:

CH₂═CHCF₂CF₂CH₂CH₂COOH,

CH₂═CHCF₂₄CH₂CH₂CH₂OH,

CH₂═CHCF₂₆CH₂CH₂COOCH₃,

[0115] and the like.

[0116] In addition, there are

[0117] and the like.

[0118] The fluorine-containing ethylenic monomer (b) having nofunctional group which is copolymerized with the fluorine-containingethylenic monomer (a) having functional group can be optionally selectedfrom known monomers, and gives heat resistance, chemical resistance,non-sticking property, stain-proofing property and friction resistanceto the polymer.

[0119] Examples of the fluorine-containing ethylenic monomer (b) aretetrafluoroethylene, a monomer represented by the formula (2):CF₂═CF—R_(f) ¹, wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² isa perfluoroalkyl group having 1 to 5 carbon atoms,chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride,hexafluoroisobutene,

CH₂═CFCF₂_(n)X², CH₂═CHCF₂_(n)X²,

[0120] wherein X² are selected from hydrogen atom, chlorine atom andfluorine atom, n are an integer of 1 to 5, and the like.

[0121] In addition to the fluorine-containing ethylenic monomer (a)having functional group and the fluorine-containing ethylenic monomer(b) having no functional group, an ethylenic monomer having no fluorineatom may be copolymerized in the range of not lowering heat resistanceand non-sticking property. In that case, it is preferable that theethylenic monomer having no fluorine atom is selected from ethylenicmonomers having not more than 5 carbon atoms in order not to lower heatresistance. Examples of such an ethylenic monomer are ethylene,propylene, 1-butene, 2-butene, and the like.

[0122] A content of the fluorine-containing ethylenic monomer (a) havingfunctional group in the fluorine-containing ethylenic polymer havingfunctional group which is used in the present invention is from 0.05 to30% by mole on the basis of the whole monomers in the polymer. Furtherthe content is optionally selected depending on kinds of the surface ofa substrate for cooking apparatuses, shape of the substrate, coatingmethod, film forming method and conditions and further depending onpurposes and applications. The content of the fluorine-containingethylenic monomer (a) having functional group is preferably from 0.05 to20% by mole, particularly preferably from 0.1 to 10% by mole.

[0123] When the content of the fluorine-containing ethylenic monomerhaving functional group is less than 0.05% by mole, sufficient adhesionto the substrate surface is difficult to obtain, and separation easilyoccurs due to temperature change and penetration of chemicals. When morethan 30% by mole, heat resistance is lowered, there occur adhesionfailure, coloring, foaming and pin hole at sintering at high temperatureor during use at high temperature, thus easily lowering property forexhibiting clear surface pattern or causing separation of a coatinglayer and elution due to decomposition.

[0124] Examples of the preferred fluorine-containing ethylenic polymerhaving functional group used in the present invention are as follows.

[0125] (I) A polymer comprising 0.05 to 30% by mole of thefluorine-containing ethylenic monomer (a-1) having functional group and70 to 99.95% by mole of tetrafluoroethylene (reactive PTFE).

[0126] The polymer is the most excellent in heat resistance, chemicalresistance and non-sticking property, and further is superior from theviewpoint of sliding property (friction resistance, abrasionresistance).

[0127] (II) A polymer comprising 0.05 to 30% by mole of thefluorine-containing ethylenic monomer (a-1) having functional groupbased on the total amount of monomers, and further based on the totalamount of monomers excluding the monomer (a-1), 85 to 99.7% by mole oftetrafluoroethylene and 0.3 to 15% by mole of a monomer represented bythe formula (2):

CF₂═CF—R_(f) ¹  (2)

[0128] wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² is aperfluoroalkyl group having 1 to 5 carbon atoms. For example, there is atetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer havingfunctional group (reactive PFA) or atetrafluoroethylene-hexafluoropropylene polymer having functional group(reactive FEP).

[0129] The polymer has heat resistance, chemical resistance andnon-sticking property nearly equivalent to those of the above-mentionedreactive PTFE (I), and further is superior from the points of possessingtransparency and being melt-processable and from the viewpoint that evenwhen coated in the form of coating, it is possible to make the coatingfilm transparent and its surface smooth by heat.

[0130] (III) A polymer comprising 0.05 to 30% by mole of thefluorine-containing ethylenic monomer (a-1) having functional groupbased on the total amount of monomers, and further based on the totalamount of monomers excluding the monomer (a-1), 40 to 80% by mole oftetrafluoroethylene, 20 to 60% by mole of ethylene and 0 to 15% by moleof other copolymerizable monomer (ethylene-tetrafluoroethylene polymer(III) having functional group (reactive ETFE)).

[0131] The polymer is superior from the viewpoint of excellent heatresistance, stain-proofing property, weather resistance andtransparency, and further excellent mechanical strength, hardness andrigidity and from the point that molding and combining with othersubstrate (lamination, etc.) are easy because of good melt-flowability.

[0132] The fluorine-containing ethylenic polymer having functional groupcan be prepared by copolymerizing the fluorine-containing ethylenicmonomer (a) having functional group and the fluorine-containingethylenic monomer (b) having no functional group through knownpolymerization methods. Among them, radical copolymerization method ismainly used. Namely means for initiating the polymerization is notparticularly limited if the polymerization advances radically. Forexample, the polymerization is initiated by an organic or inorganicradical polymerization initiator, heat, light, ionizing radiation, etc.The polymerization can be carried out by solution polymerization, bulkpolymerization, suspension polymerization, emulsion polymerization, orthe like. A molecular weight of the polymer is regulated by aconcentration of the monomers used in the polymerization, aconcentration of the initiator, and a concentration of a chain transferagent and polymerization temperature. Amounts of components of theprepared copolymer can be regulated by amounts of monomers used.

[0133] The fluorine-containing ethylenic polymer having functional groupand explained above can be made into various forms as a material to beapplied to a substrate. Represented examples of its application are acoating material or a material in the form of film. The polymer may beformed into a molded article.

[0134] In the present invention, the above-mentioned fluorine-containingethylenic polymer having functional group can be applied to a substratein the form of coating to give a composite material for cookingapparatuses.

[0135] In the present invention, in case of use in the form of coating,the polymer is capable of being in the form of aqueous dispersion,organic solvent dispersion, powder (including granulate), organosol oran aqueous emulsion of organosol. Among them, from environmental andsafety points of view, it is preferable to apply in the form of anaqueous dispersion or powder (powder coating).

[0136] The coating may be applied so that excellent adhesive property ofthe fluorine-containing ethylenic polymer having functional group to thesubstrate is exhibited. The coating may be applied in one layer or as aprimer.

[0137] In the present invention, the aqueous dispersion forfluorine-containing coating composition is prepared by dispersing, inwater, particles of the above-mentioned fluorine-containing ethylenicpolymer having functional group. By introducing a functional group inthe fluorine-containing polymer, dispersion stability of fine particlesin the aqueous dispersion is enhanced and a coating composition havinggood storage stability can be obtained, and further leveling propertyand transparency of a coating film are enhanced.

[0138] As the fluorine-containing ethylenic polymer having functionalgroup, from the viewpoint of heat resistance, non-sticking property, andfriction resistance, the reactive PTFE (I) is preferred, and from theviewpoint of heat resistance, non-sticking property and transparency,the reactive PFA or reactive FEP (II) is preferred.

[0139] The above-mentioned aqueous dispersion is preferably in a stateof 0.01 to 1.0 μm fine particles of the polymer being dispersed inwater. A surfactant may be blended in the aqueous dispersion for thepurpose of dispersion stability. Also to the aqueous dispersion can beadded additives to be used usually such as pigment, surfactant,defoaming agent, viscosity control agent and leveling agent in amountsnot lowering remarkably heat resistance, chemical resistance,non-sticking property and friction resistance.

[0140] The aqueous dispersion for fluorine-containing coatingcomposition can be prepared through various methods. Examples of themethod are, for instance,

[0141] a method wherein a powder of the fluorine-containing polymerhaving functional group and prepared by suspension polymerization isfinely pulverized and then the pulverized powder is dispersedhomogeneously into an aqueous dispersion medium with a surfactant,

[0142] a method wherein a fluorine-containing aqueous dispersion isprepared at the same time as emulsion polymerization and further asurfactant and additives are added as the case demands, and the likemethods. From the viewpoint of productivity and quality (for makingparticle size smaller and more uniform), a method of preparing anaqueous dispersion directly by emulsion polymerization is preferred.

[0143] A concentration of the polymer in the aqueous dispersion variesdepending on desired coating thickness, concentration and viscosity of acoating composition, coating method, etc., and is usually selected inthe range of from about 5% by weight to about 70% by weight.

[0144] The coating method is not particularly limited. The coating maybe carried out by brush coating, spray coating, roll coating or thelike, and then dried and sintered at a temperature of not less than themelting point of the polymer and not more than its decompositiontemperature depending on kind of the polymer.

[0145] The coating thickness may be selected depending on application,purpose, substrate, etc. For example, the coating thickness is fromabout 5 μm to about 200 μm, preferably from 10 to 100 μm.

[0146] The powder coating composition of the present invention comprisesa powder of the above-mentioned fluorine-containing ethylenic polymerhaving functional group.

[0147] Further from the viewpoint of heat resistance, non-stickingproperty, corrosion resistance and chemical resistance, the reactive PFAor reactive FEP (II) is preferred, and from the viewpoint ofstain-proofing property, processability and transparency, the reactiveETFE (III) is preferred.

[0148] As the fluorine-containing powder coating composition, there canbe used preferably one in the form of powder or in the granular formhaving a particle size of 10 to 1,000 μm and an apparent density of 0.3to 1.2 g/cc.

[0149] To the fluorine-containing powder coating composition can beadded optionally additives in amounts not lowering remarkablycharacteristics such as heat resistance of the fluorine-containingresin. Examples of the additives are, for instance, pigments such ascarbon powder, titanium oxide and cobalt oxide; reinforcing agents suchas glass fiber powder, carbon fiber powder and mica; amine anti-oxidant;organic sulfur anti-oxidant; organotin anti-oxidant; phenolicanti-oxidant; thermal stabilizer such as metal soap; leveling agent;anti-static agent; and the like.

[0150] The fluorine-containing powder coating composition and theadditives may be admixed in the form of powder (dry method) or in theform of slurry (wet method), and the mixing in the form of powder ispreferred. As the mixing equipment, there can be used a conventionalmixer or pulverizer, for example, a sand mill, V blender, ribbon blenderor the like.

[0151] The fluorine-containing powder coating composition is generallycoated by electrostatic spray coating, fluidized-bed dip coating,rotolining, etc., and then sintered at a temperature of not less thanthe melting point of the polymer and not more than its decompositiontemperature depending on kind of the polymer, and thus a good coatingfilm can be formed.

[0152] In general in case of electrostatic powder spray coating, acoating film having a thickness of 10 to 200 μm is formed, and in caseof rotolining, a coating film having a thickness of 200 to 1,000 μm isformed.

[0153] Further the fluorine-containing ethylenic polymer havingfunctional group which is used for a fluorine-containing coatingmaterial can be used, by utilizing its adhesive property, as a primerlayer for a fluorine-containing coating composition which has good heatresistance at the time when applying a fluorine-containing resin havingno functional group on surfaces of substrates such as metal and glass.

[0154] The primer for a fluorine-containing coating compositioncomprises the above-mentioned fluorine-containing ethylenic polymerhaving functional group.

[0155] As the primer, the same fluorine-containing polymer as mentionedabove can be used. The primer is selected optionally depending on kindof a substrate surface, kind of the fluorine-containing polymer to beapplied through the primer (kind of a top coat), etc. It is preferablein general that the primer for a fluorine-containing coating compositionis one which has the same structure as the fluorine-containing polymerto be applied thereon and contains a functional group.

[0156] That combination of the primer and top coat assures goodcompatibility between the fluorine-containing polymer to be used as theprimer and the fluorine-containing polymer to be applied thereon, andcan give not only good adhesion to the substrate surface but also goodintercoat adhesive strength between the primer layer and the top coatlayer. Also even in case of the use at high temperature, unlike the casewhere the primer mixed with other resin component is used, intercoatadhesion failure to be caused due to a difference in thermal shrinkagebetween the polymers, cracking, pin hole, etc. are hard to arise.Further since the whole coating film comprises the fluorine-containingpolymer, it can be used sufficiently for applications requiringtransparency and vivid coloring. Still further excellent heatresistance, chemical resistance, non-sticking property and frictionresistance can be exhibited more effectively even if a layer offluorine-containing polymer having no functional group is formed on theoutermost surface of the coating film.

[0157] Examples of the fluorine-containing polymer having no functionalgroup and used for a top coat layer are PTFE, PFA, FEP, ETFE, PVdF andVdF copolymers.

[0158] As the primer for fluorine-containing coating composition, therecan be used the above-mentioned fluorine-containing ethylenic polymerhaving functional group. In case where a substrate is coated with PTFE,it is preferable to use the primer selected from the reactive PTFE (I),reactive PFA and reactive FEP (II). It is particularly preferable touse, as the primer, thermo-melting reactive PFA or FEP (II) since it ispossible to thermo-melt and strongly adhere to a substrate surface bysintering. In case where a substrate is coated with PFA or FEP, it ispreferable to use, as the primer, reactive PFA or FEP (II). Further incase where a substrate is coated with ETFE, it is particularlypreferable to use, as the primer, reactive ETFE (III) from the viewpointof adhesion and transparency.

[0159] As a coating method using a primer layer, there can be usedpreferably a method of coating a fluorine-containing polymer, whichmainly comprises the following three steps;

[0160] (First step) a step for applying, to a substrate surface, theprimer for fluorine-containing coating composition comprising theabove-mentioned fluorine-containing polymer having functional group,

[0161] (Second step) a step for applying a fluorine-containing coatingcomposition comprising a fluorine-containing polymer having nofunctional group, to the primer layer formed in the above first step,and

[0162] (Third step) a step for sintering the laminated article obtainedin the above first and second steps.

[0163] Further the primer layer applied in the above first step may beset by drying at 80° to 150° C. for about 5 minutes to about 30 minutesprior to the second step (2 coats/1 bake) or may be sintered, forexample, at a temperature higher than the melting temperature thereofprior to the second step (2 coats/2 bakes).

[0164] The method for applying the primer in the first step isoptionally selected depending on the form of the primer. For example, incase where the fluorine-containing primer is in the form of aqueousdispersion, spray coating, spin coating, brush coating and dip coatingmethods are used. Also in case of the form of powder coatingcomposition, coating methods such as electrostatic coating, fluid-beddip coating and rotolining are employed.

[0165] A thickness of the primer layer may vary depending on purpose,application, kind of a substrate surface and form of the primer. Thethickness is from 1 to 50 μm, preferably from 2 to 20 μm. Since thethickness of the primer is in general thin as mentioned above, it ispreferable to coat the primer in the form of aqueous dispersion by spraycoating, etc.

[0166] The method for applying the coating composition comprising afluorine-containing polymer having no functional group to the primerlayer in the second step is optionally selected depending on kind of thefluorine-containing polymer, form of the coating, purpose andapplication. For example, in case of an aqueous dispersion and organicsolvent dispersion, usually spray coating, brush coating, roll coatingand spin coating are carried out. In case of a powder coatingcomposition, electrostatic coating, fluid-bed dip coating or rotoliningare carried out.

[0167] A coating thickness of the fluorine-containing polymer in thisstep varies largely depending on purpose, application and coatingmethod. The thickness is in general from 5 to 50 μm, preferably fromabout 10 μm to about 30 μm in case of spray coating. When a thickcoating film is desired by using a powder coating composition, it ispossible to apply at 20 to 2,000 μm thick in case of electrostaticcoating, and at 0.3 to 10 μm thick in case of rotolining.

[0168] Sintering conditions in the third step are optionally selecteddepending on kinds of fluorine-containing polymers (component, meltingpoint, etc.) of the primer layer and the top layer thereon. Thesintering is carried out in general at a temperature of not less thanthe melting point of the both fluorine-containing polymers. A sinteringtime varies depending on the sintering temperature, and is from fiveminutes to three hours, preferably from about 10 minutes to about 30minutes. For example, when coating with PTFE, PFA and FEP, sintering iscarried out at 320° to 400° C., preferably 350° to 400° C.

[0169] Then technique for applying the above-mentionedfluorine-containing ethylenic polymer having functional group in theform of film to produce a composite material for cooking apparatuses isexplained.

[0170] Merits of applying in the form of film are as follows.

[0171] {circle over (1)} A film comprising a fluorine-containingethylenic polymer having functional group is advantageous from theviewpoint of processing since an applicator necessary for a hot-meltadhesive is not required, and the film can be adhered bythermocompression bonding while being put on a substrate or insertedbetween substrates.

[0172] {circle over (2)} Further since a uniform adhesive layer isformed on the whole surface of substrate, a film free from nonuniformadhesion and having uniform adhesive strength can be obtained, and thuscan be applied to a substrate having poor or no compatibility therewith.

[0173] {circle over (3)} Further the film can be cut into variousshapes, and thus is advantageous from the viewpoint of a small loss inprocessing work, good working environment and cost.

[0174] The preferred fluorine-containing polymer film of the presentinvention may be one which is produced by molding the above-mentionedfluorine-containing ethylenic polymer having functional group. The filmcan be adhered to various substrates without surface treating and usingusual adhesives, thereby giving excellent characteristics of thefluorine-containing polymer to a substrate.

[0175] Though it is possible to produce adhesive films from theabove-mentioned fluorine-containing polymers having functional group byusing various adhesives depending on application, purpose, filmproduction process and adhering method, the above-mentioned copolymer(III) (reactive PFA or reactive FEP) or copolymer (IV) (reactive ETFE)is preferred since the adhesive film itself has heat resistance,chemical resistance, mechanical properties and non-sticking property;efficient film molding represented by melt-molding can be carried out;the film has good moldability; making the film thin and uniform ispossible; and it is possible to melt the film by variousthermocompression bonding methods to adhere strongly and beautifully tovarious substrates. Particularly preferred functional group is hydroxylfrom the viewpoint of heat resistance.

[0176] A thickness of the fluorine-containing film is selected dependingon purpose and application and is not limited particularly. Thethickness is from 10 to 3,000 μm, preferably from 20 to 500 μm,particularly preferably from 40 to 300 μm.

[0177] In case of too thin films, special production method is required;it is difficult to handle the film at the time of adhering; wrinkling,breaking and poor appearance occur easily; and there is a case whereadhesive strength, mechanical strength, chemical resistance and weatherresistance become insufficient. Too thick film is disadvantageous fromthe viewpoint of cost and workability at the time of bonding to oneunit.

[0178] In the present invention, the fluorine-containing polymer filmmay be used alone or can be used in the form of laminated filmcomprising the film (adhesive layer) of fluorine-containing ethylenicpolymer having functional group and the film (surface layer) offluorine-containing ethylenic polymer having no functional group.

[0179] Namely one surface of the film is a layer comprising afluorine-containing ethylenic polymer having functional group and hasadhesive property to other substrate, and another surface of the film isa layer comprising usual fluorine-containing polymer. By bringing thesurface of the fluorine-containing ethylenic polymer having functionalgroup into contact to the substrate and adhering it to the substrate bythermocompression bonding, etc., excellent characteristics of thefluorine-containing polymer such as non-sticking property,stain-proofing property, friction resistance, weather resistance andchemical resistance can be given to the substrate for cookingapparatuses or the composite material comprising the substrate.

[0180] In the present invention, a thickness of the two-layeredlaminated film of fluorine-containing polymer is selected depending onpurpose and application, and is not limited particularly. The totalthickness of two layers is from 20 to 5,000 μm, preferably from 40 to1,000 μm, particularly preferably from 100 to 500 μm.

[0181] A thickness of each layer which can be used is from 5 to 1,000μm, preferably from 10 to 500 μm, particularly preferably from 10 to 200μm of the adhesive layer, and from about 15 μm to about 4,995 μm,preferably from 30 to 990 μm, particularly preferably from 90 to 490 μmof the fluorine-containing polymer layer (surface layer).

[0182] The film for the surface layer may be adhered after adhering thefilm for the adhesive layer to a substrate.

[0183] To the film of fluorine-containing polymer having functionalgroup can be optionally incorporated proper additives such as areinforcing agent, filler, stabilizer, ultraviolet ray absorber,pigment, etc. in an amount not lowering characteristics of the film.Those additives make it possible to improve thermal stability, surfacehardness, abrasion resistance, weather resistance and electrostaticcharge, etc.

[0184] The fluorine-containing film of the present invention can beproduced, depending on kind of polymers used and desired shape of thefilm, by various methods such as thermal melting method, extrusionmethod, cutting method, solvent-casting method and a method of applyinga powder or an aqueous dispersion or organic solvent dispersion to forma continuous coating film.

[0185] For example, a polymer which comprises the above-mentionedreactive PTFE and is difficult to be melt-molded can be molded bycompression molding, extrusion molding (ram extrusion, paste extrusion,roll press, etc.) or the like. A polymer such as reactive PFA, FEP orETFE which is melt-moldable is molded by compression molding andextrusion molding, and melt-extrusion molding is particularly preferredfrom the viewpoint of productivity and product quality.

[0186] Namely one surface of the film is a layer comprising afluorine-containing ethylenic polymer having functional group and hasadhesive property to other substrate, and another surface of the film isa layer comprising usual fluorine-containing polymer. By bringing thesurface of the fluorine-containing ethylenic polymer having functionalgroup into contact to the substrate and adhering it to the substrate bythermocompression bonding, etc., excellent characteristics of thefluorine-containing polymer such as chemical resistance, weatherresistance, stain-proofing property, non-sticking property, frictionresistance and electrical properties (high-frequency electric insulationproperty) can be given to the substrate or the composite materialcomprising the substrate.

[0187] In the present invention, a thickness of the two-layeredlaminated film of fluorine-containing polymer is selected depending onpurpose and application, and is not limited particularly. The totalthickness of two layers is from 20 to 5,000 μm, preferably from 40 to1,000 μm, particularly preferably from 100 to 500 μm.

[0188] A thickness of each layer which can be used are from 5 to 1,000μm, preferably from 10 to 500 μm, particularly preferably from 10 to 200μm of the adhesive layer, and from about 15 μm to about 4,995 μm,preferably from 30 to 990 μm, particularly preferably from 90 to 490 μmof the fluorine-containing polymer layer (surface layer).

[0189] The film for the surface layer may be adhered after adhering thefilm for the adhesive layer to a substrate.

[0190] To the film of fluorine-containing polymer having functionalgroup can be optionally incorporated proper additives such as areinforcing agent, filler, stabilizer, ultraviolet ray absorber,pigment, etc. in an amount not lowering characteristics of the film.Those additives make it possible to improve thermal stability, surfacehardness, abrasion resistance, weather resistance and electrostaticcharge, etc.

[0191] The fluorine-containing film of the present invention can beproduced, depending on kind of polymers used and desired shape of thefilm, by various methods such as thermal melting method, extrusionmethod, cutting method, solvent-casting method and a method of applyinga powder or an aqueous dispersion or organic solvent dispersion to forma continuous coating film.

[0192] For example, a polymer which comprises the above-mentionedreactive PTFE and is difficult to be melt-molded can be molded bycompression molding, extrusion molding (ram extrusion, paste extrusion,roll press, etc.) or the like. A polymer such as reactive PFA, FEP orETFE which is melt-moldable is molded by compression molding andextrusion molding, and melt-extrusion molding is particularly preferredfrom the viewpoint of productivity and product quality.

[0193] Bonding of the two films into one laminated film can be carriedout by a method of overlapping the respective molded films for adhesivelayer and surface layer and then compression-molding; a method ofapplying, to a molded film, the other one; a method of carrying out filmmolding and bonding of films at the same time through multi-layerco-extrusion molding method, or the like method. Among them, themulti-layer co-extrusion molding method is preferred from the viewpointof productivity and product quality.

[0194] Adhesion of the film of fluorine-containing polymer havingfunctional group to a substrate is achieved through thermal activationby heating, etc. Further thermo-melting adhesion is preferable.Represented examples of the adhering method are heating roller methodand heat press method. Also there are other methods such ashigh-frequency heating, microwave heating, vacuum compression (vacuumpress, etc.) and pneumatic press. Those methods can be optionallyselected depending on kind and shape of a substrate, condition and kindof film, etc.

[0195] Examples of the substrate on which the fluorine-containingpolymer having functional group can be adhered, are a metallicsubstrate, ceramic substrate, resin substrate, and the like.

[0196] Metals of the metallic substrate encompass metal, alloys of twoor more metals, metal oxide, metal hydroxide, metal salts such ascarbonate and sulfate, etc. Among them, metal, metal oxide and alloysare more preferable from the viewpoint of adhesive property.

[0197] Examples of the metallic substrate are metals and metal compoundsof aluminum, iron, nickel, titanium, molybdenum, magnesium, manganese,copper, silver, lead, tin, chromium, beryllium, tungsten and cobalt,alloys of two or more thereof, etc.

[0198] Examples of the alloys are alloy steels such as carbon steel, Nisteel, Cr steel, Ni—Cr steel, Cr—Mo steel, stainless steel, siliconsteel and Permalloy; aluminum alloys such as Al—Cl, Al—Mg, Al—Si,Al—Cu—Ni—Mg and Al—Si—Cu—Ni—Mg; copper alloys such as brass, bronze,silicon bronze, silicon brass, nickel silver and nickel bronze; nickelalloys such as nickel manganese (D nickel), nickel-aluminum (Z nickel),nickel-silicon, Monel metal, Constantan, nichrome Inconel and Hastelloy;and the like.

[0199] Further as the aluminum-based metal, there can be used purealuminum; aluminum oxide; and aluminum alloys for casting and expandingsuch as Al—Cu, Al—Si, Al—Mg, Al—Cu—Ni—Mg, Al—Si—Cu—Ni—Mg alloys, hightensile aluminum alloy and corrosion resistant aluminum alloy.

[0200] Also as the iron-based metals, there can be used pure iron, ironoxide, carbon steel, Ni steel, Cr steel, Ni—Cr steel, Cr—Mo steel,Ni—Cr—Mo steel, stainless steel, silicon steel, Permalloy, non-magneticsteel, magnet steel, cast iron, etc.

[0201] Also the fluorine-containing polymer having functional group canbe adhered to a substrate which was subjected to, for the purpose ofpreventing corrosion of metal, coating of other metal by electroplating,hot dipping, chromatizing, siliconizing, colorizing, sheradizing, metalspraying, etc.; forming a phosphate film by phosphatization; formingmetal oxide by anodizing or heat-oxidizing; or electrochemical corrosionprevention.

[0202] Further for the purpose of enhancing adhesion, the surface ofmetallic substrate may be subjected to chemical preparation with aphosphoric acid, sulfuric acid, chromic acid, oxalic acid, etc., or maybe subjected to surface roughening by sand blasting, shot blasting, gritblasting, honing, paper scratching, wire scratching, hair linefinishing, etc. For the purpose of exhibiting clear surface pattern ofthe substrate, the metal surface may be subjected to coloring, printing,etching, etc.

[0203] In case of the above-mentioned aluminum or aluminum alloysubstrate, in order to enhance corrosion resistance, surface hardnessand adhesive property of the substrate, it is possible to form an oxidefilm (alumite) on the substrate by anodizing with caustic soda, oxalicacid, sulfuric acid or chromic acid and also use the aluminum oraluminum alloy substrate subjected to other surface treatments mentionedabove.

[0204] Further there may be used a substrate plated, on its surface,other metal as mentioned above, for example, steel plate subjected tohot-dip zinc-plating, hot-dip zinc alloy plating, aluminum plating,zinc-nickel plating, zinc-aluminum plating, or the like; a substratecoated with other metal by diffusion coating or thermal spraying; asubstrate, on which an oxide film is formed by chemical conversiontreatment with chromic acid or phosphoric acid or heat-treatment; asubstrate subjected to electric corrosion preventing treatment (forexample, galvanized steel plate); or the like.

[0205] Examples of the ceramic substrate are, for instance, glass,pottery, porcelain, etc.

[0206] Components of glass are not particularly limited. Examples aresilica glass, lead glass, non-alkali glass, alkali glass, etc.

[0207] Examples of the resin substrate are, for instance, an acrylicresin, polycarbonate, heat resistant engineering plastic, thermosettingresin, etc.

[0208] Examples of the above-mentioned substrate used usually for thecomposite material for cooking apparatuses of the present invention as ametallic substrate are, for instance,

[0209] {circle over (1)} cold rolled steel sheet,

[0210] {circle over (2)} plated steel sheet, for example, Zn-platedsteel sheet, Zn alloy-plated steel sheet, Al-plated steel sheet, Alalloy-plated steel sheet, Cr-plated steel sheet (TFS), Ni-plated steelsheet, Cu-plated steel sheet, galvanized steel sheet, etc.,

[0211] {circle over (3)} aluminum sheet,

[0212] {circle over (4)} titanium sheet,

[0213] {circle over (5)} stainless steel sheet,

[0214] and the like.

[0215] In addition, where transparency is required, a ceramic substrateof glass and a resin substrate of acrylic resin and polycarbonate areusually used.

[0216] It is preferable that the form of the substrate is the same as aform of a finished product from the viewpoint that there is a case whereprocessability is difficult depending on kind of cooking apparatuses.

[0217] The composite material of the present invention can be used onvarious cooking apparatuses firstly because the fluorine-containingresin is applied to a substrate with good adhesive property andsecondary because the fluorine-containing resin possesses goodtransparency (clear surface pattern), heat resistance, non-stickingproperty, stain-proofing property, water- and oil repelling property,and the like.

[0218] Cooking apparatuses and parts thereof to which the compositematerial for cooking apparatuses of the present invention can besuitably applied are classified by fields they belong to, andexemplified below. Accordingly the present invention also relates tocooking apparatuses and parts thereof mentioned below.

[0219] Also those classified cooking apparatuses and parts thereof areshown in Tables 1 to 7.

[0220] {circle over (1)} Pots and Pans

[0221] (a) Inner Surface, Inner Lid, etc. of Electric Pot IncludingElectric Water Heater

[0222] In those applications, stain-proofing property (for fur), hotwater resistance and antibacterial property of the composite materialfor cooking apparatuses of the present invention can be usedparticularly effectively.

[0223] (b) Inner Surface of Inner Pot, Inner Lid, etc. of Gas andElectric Rice Cookers and Rice Cookers with Rice Washing Mechanism, etc.

[0224] In those applications, non-sticking property (for rice andscorching) and heat resistance of the composite material for cookingapparatuses of the present invention can be used particularlyeffectively.

[0225] {circle over (2)} Cooking Apparatuses

[0226] (a) Surfaces of Frying Pan, Vat, Household Hand Mixer forCooking, Crate, Kitchen Knife, Molder for Bread, Reverse Sheet forRolling Dough, Dough Dividing and Rounding Machine for Bread, etc.,Inner Surface of Mixing Bowl, Rice Chest, etc. and Blade of theAbove-Mentioned Mixer

[0227] In those applications, non-sticking property (scorching andcohering stains), stain-proofing property and heat resistance of thecomposite material for cooking apparatuses of the present invention canbe used particularly effectively.

[0228] (b) Inner Surface, Blade, etc. of Electric Food Processors Suchas Electric Food Crusher for Domestic Use, Electric Food Crusher,Electric Meat Grinder for Kitchen Use, Electric Blender for Kitchen Useand Electric Mixer for Kitchen Use

[0229] In those applications, non-sticking property (for vegetable andmeat juice) and stain-proofing property of the composite material forcooking apparatuses of the present invention can be used particularlyeffectively.

[0230] {circle over (3)} Gas Range with Grill

[0231] (a) Top Panel, Side Panel, Surface of Gas Ranges such as GasContainer Built-In Type Range, and Drip Pan Cover thereof, etc.

[0232] In those applications, non-sticking property (for oil stains),heat resistance and transparency (property for exhibiting clear colorand pattern) of the composite material for cooking apparatuses of thepresent invention can be used particularly effectively.

[0233] {circle over (4)} Ranges with Oven Including Toaster, Range, etc.

[0234] (a) Inner Surfaces (Metallic Portion) of Ovens (Range forKitchen) such as Oven for Shop Use, Electric Oven (Including Oven forShop Use), Electric Oven with Heating Cabinet for Shop Use, Cooking Ovenfor Shop Use and Cooking Range for Shop Use; Ovens for Making Bread suchas Baking Oven for Shop Use and Automatic Baking Apparatus for DomesticUse; Electric Oven and Toaster such as Toaster and Toaster for Bread;and Microwave Range such as Microwave Range for Shop Use and MicrowaveRange with Oven; and Pans for Ranges

[0235] In those applications, non-sticking property (for oil andscorching), stain-proofing property and heat resistance of the compositematerial for cooking apparatuses of the present invention can be usedparticularly effectively.

[0236] (b) Inner Surface of Door of Ranges with Oven Raised in Above (a)

[0237] In those applications, non-sticking property, heat resistance andtransparency of the composite material for cooking apparatuses of thepresent invention can be used particularly effectively. In case ofmicrowave range, energy ray resistance can be used particularlyeffectively.

[0238] {circle over (5)} Pots and Pans

[0239] (a) Inner Surface of Pots and Pans such as Glass Pot, EnameledPot, Aluminum Pot, Electric Frying Pot, Electric Tempura Pot, ElectricPressure Pot and Electric Pressure Pot for Stew, etc.

[0240] In those applications, non-sticking property (for scorching,cohering stains and oil in case of the frying pot and Tempura pot) andheat resistance of the composite material for cooking apparatuses of thepresent invention can be used particularly effectively.

[0241] (b) Lid, etc. of Pots and Pans Raised in Above (a)

[0242] In those applications, not only the characteristics raised inabove (a) but also transparency of the composite material for cookingapparatuses of the present invention can be used particularlyeffectively.

[0243] {circle over (6)} Garbage Disposer

[0244] Inner surface, etc. of garbage disposer for domestic use andgarbage (waste) disposer for making compost.

[0245] In those applications, non-sticking property and stain-proofingproperty of the composite material for cooking apparatuses of thepresent invention can be used particularly effectively.

[0246] {circle over (7)} Other Heating Apparatuses for Cooking

[0247] (a) Heating Surface, Lid, etc. of Griddle

[0248] In those applications, non-sticking property (for scorching andcohering stains) and heat resistance of the composite material forcooking apparatuses of the present invention and transparency thereof incase of the lid can be used particularly effectively.

[0249] (b) Cooking Surface, etc. of Electromagnetic Cooking Apparatusessuch as Electromagnetic Range and Oven

[0250] In those applications, non-sticking property, heat resistance andtransparency of the composite material for cooking apparatuses of thepresent invention can be used particularly effectively.

[0251] (c) Inner Surface, Door Inner Surface, Lid, etc. of ElectricSteamer such as Food Steamer for Shop Use

[0252] In those applications, non-sticking property, stain-proofingproperty, heat resistance and steam resistance of the composite materialfor cooking apparatuses of the present invention can be usedparticularly effectively.

[0253] (d) Inner Surface, Lid, etc. of Noodle Boiler for Shop Use

[0254] In those applications, non-sticking property, stain-proofingproperty, heat resistance and hot water resistance of the compositematerial for cooking apparatuses of the present invention can be usedparticularly effectively.

[0255] (e) Inner Surface, Inner Surface (Metallic Portion) and DoorInner Surface of Cooking Roaster for Shop Use, Pan for Range, etc.

[0256] In those applications, non-sticking property (for scorching andcohering stains) and heat resistance of the composite material forcooking apparatuses of the present invention can be used particularlyeffectively.

[0257] (f) Inner Surface, etc. of Tableware and Can Washer for Shop Use

[0258] In those applications, non-sticking property, stain-proofingproperty and hot water resistance of the composite material for cookingapparatuses of the present invention can be used particularlyeffectively.

[0259] (g) Inner Surface, Door Inner Surface, etc. of Heating Cabinetfor Shop Use

[0260] In those applications, non-sticking property, stain-proofingproperty, transparency and heat resistance of the composite material forcooking apparatuses of the present invention can be used particularlyeffectively.

[0261] Further examples of the cooking apparatuses other than thosementioned above, to which the composite material for cooking apparatusesof the present invention can be preferably applied, are as follows.

[0262] Examples of cooking apparatuses within the range of above {circleover (1)} (b) are rice gruel cooker, rice warmer, etc.

[0263] Examples of cooking apparatuses within the range of above {circleover (2)} (a) are various cooking utensils (for slicing), cookingutensils, cooking appliance, cooking machine (for food, etc.), ironplate for cooking, cooking appliances and facilities, barbecue utensils,food processing machine (with press machine, etc.), chocolatemanufacturing machine and ancillary temperature adjusting equipmentthereof for starting material, etc.

[0264] Examples of cooking appliances within the range of above {circleover (2)} (b) are cooking appliance for mixing, vegetable slicer, foodslicer, peeler, machine for cutting into cubes, food cutter, meatchopper, meat slicer, meat tenderizer, cutter mixer, mixer, food mixer,blender, apple processor, continuous egg opener, soy bean curd cutter,bread crumb coating machine, vegetable washer, etc.

[0265] Examples of cooking apparatuses within the range of above {circleover (3)} are range, portable heater, electric range, gas range, gasoven with grill, electric oven with grill, etc.

[0266] Examples of cooking apparatuses within the range of above {circleover (4)} are gas salamander, electric salamander, convention oven,baking oven for making bread, etc.

[0267] Examples of cooking apparatuses within the range of above {circleover (5)} are wok set for Chinese dishes, one-handed pot, double-handedpot, gas fryer, Tempura fryer, oil filter unit, buckwheat pot, rotarypot, etc.

[0268] Examples of cooking apparatuses within the range of above {circleover (7)} are fryer for dumpling stuffed with minced meat,electromagnetic range, gas steamer, electric steamer, etc. TABLE 1Classifi- Typical cation finished Characteristics Defects of Effect ofthe of product product needed prior art invention Pots ElectricStain-proofing Primer is Adhesive pot property for necessary. property,fur, hot water Process- processabil- resistance, ability is ity (noantibacterial not good primer property and surface required) pattern isunclear. Electric Non-sticking Primer is Adhesive rice cooker propertyfor necessary. property, scorched rice, Process- processabil- heatresistance ability is ity (no not good primer and surface required)pattern is unclear. Cooking Frying pan Non-sticking Process- Adhesiveappliances property for ability and property, and utensils scorch andtransparency processabil- cohered stain, are not good ity (nostain-proofing and surface primer property, heat pattern is required),resistance unclear. transparency, clearer surface pattern Electric foodNon-sticking Process- Adhesive processor property for ability andproperty, vegetable and transparency improvement juice of meat, are notgood of process- stain-proofing and surface ability (no property patternis primer unclear. required), transparency, clearer surface pattern Ovenwith Gas oven Non-sticking Process- Adhesive grill property for abilityis not property, stained oil, good and process- heat resistance surfaceability (no transparency, pattern is primer clear surface unclear.required), (color, pattern) transparency, clear surface pattern Rangewith Oven Non-sticking Process- Adhesive oven (kitchen property for oilability, heat property (toaster, range) and scorch, resistance(processabil- range) stain-proofing and durabil- ity), clear property,heat ity are not surface resistance, non- good. Wipe- pattern, stickingoff property transparency property, is not good transparency (Noarticles treated with fluorine-con- taining resin are avail- able).Trans- parency is not good. Oven for Non-sticking Process- Adhesivebaking bread property for oil ability, heat property and scorch,resistance (processabil- stain-proofing and durabil- ity), clearproperty, heat ity are not surface resistance, non- good. Wipe- pattern,sticking off property transparency property, is not good transparency(No articles treated with fluorine-con- taining resin are avail- able).Trans- parency is not good. Electric oven Non-sticking Process- Adhesiveand toaster property for oil ability, heat property and scorch,resistance (processabil- stain-proofing and durabil- ity), clearproperty, heat ity are not surface resistance, non- good. Wipe- pattern,sticking off property transparency property, is not good transparency(No articles treated with fluorine-con- taining resin are avail- able).Trans- parency is not good. Microwave Non-sticking Process- Adhesiveoven property, heat ability, heat property resistance, resistance(processabil- resistance to and durabil- ity), heat energy ray, ity arenot resistance, transparency good. Wipe- durability, off propertymaintenance is not good of transpar- (No articles ency treated withfluorine-con- taining resin are avail- able). Trans- parency is notgood.

[0269] TABLE 2 Classifi- Typical cation finished Characteristics Defectsof Effect of the of product product needed prior art invention Pot andpan Glass pot Non-sticking Wipe-off Adhesive property for property isproperty scorch and not good (No (processabil- cohering stains, articlesity), trans- heat resistance, treated with parency transparencyfluorine- containing resin are available). Heat resist- ance andtransparency are not good. Electric deep Non-sticking Processabil-Adhesive fryer property for ity, heat property, oil, heat resistanceprocessabil- resistance, and wipe-off ity (no transparency property areprimer not good (No required), articles transparency treated withfluorine- containing resin are available). Surface pattern is unclear.Transpar- ency is not good. Electric pres- Non-sticking Processabil-Adhesive sure pot property ity, heat property, for scorching resistanceprocessabil- and cohering and wipe-off ity (no stains, heat property areprimer resistance, not good (No required), transparency articlestransparency treated with fluorine- containing resin are available).Surface pattern is unclear. Transpar- ency is not good. Electric pres-Non-sticking Processabil- Adhesive sure pot for property ity, heatproperty, stew for scorching resistance processabil- and cohering andwipe-off ity (no stains, heat property are primer resistance, not good(No required), transparency articles transparency treated with fluorine-containing resin are available). Surface pattern is unclear. Transpar-ency is not good.

[0270] TABLE 3 Classifi- Typical cation finished Characteristics Defectsof Effect of the of product product needed prior art invention OtherGriddle Non-sticking Processabil- Adhesive heating property for ity,abrasion property, appliances scorch and resistance processabil- forcooking cohering stains, and heat ity (no heat resistance, resistanceprimer non-sticking are not good. required), property, Wipe-off heatresist- transparency property is ance, abra- not good (No sion resist-articles ance, trans- treated with parency fluorine- containing resinare available). Transpar- ency is not good. Electro- Non-stickingProcessabil- Adhesive magnetic property, heat ity is not property,cooking resistance, good. processabil- appliance transparency ity (noprimer required), transparency Electric Non-sticking Processabil-Adhesive cooking property, stain- ity is not property, steamer proofinggood. processabil- property, ity (no heat resist- primer ance, steamrequired) resistance Noodles Non-sticking boiling property, stain-Processabil- Adhesive apparatus for proofing ity is not property, shopuse property, good. processabil- heat resist- ity (no ance, hot waterprimer resistance required) Other Cooking Non-sticking Processabil-Adhesive heating roaster for property for ity and heat property,applicances shop use scorch and resistance processabil- for cookingcohering stains, are not good. ity (no heat resistance primer required),transparency Tablewares Non-sticking Processabil- Adhesive and cansproperty, stain- ity is not property, washing proofing prop- good.processabil- machine for erty, hot water Surface ity (no shop useresistance pattern primer is unclear. required) Heat cabinetNon-sticking Processabil- Adhesive for shop use property, stain- ity andtrans- property, proofing prop- parency are processabil- erty, trans-not good. ity (no parency, Surface primer heat resistance pattern isrequired) unclear. Garbage Garbage Non-sticking Processabil- Adhesivedisposer disposer property, stain- ity is not property, proofing good.processabil- property Surface ity (no pattern primer is unclear.required)

[0271] TABLE 4 Classifi- Typical cation of finished product productSimilar product Application Pots Electric pot Inner surface, inner lidElectric water heater Inner surface, inner lid Electric rice Innersurface of inner cooker pot, inner lid Rice cooker (gas, Inner surfaceof inner electric) pot, inner lid Rice cooker (with Inner surface ofinner rice washing mech- pot, inner lid anism for shop use) CookingFrying pan Surface appliances Vat Surface and utensils Mixing bowl Innersurface Chopping board Surface Household hand- Surface, blade operatedmixer for cooking Crate Surface Cooking knife Surface Molder for makingSurface bread Reverse sheet for Surface making bread Dough dividing andSurface rounding machine for making bread Rice chest Inner surfaceElectric food Inner surface, blade processor Household electric Innersurface food crusher Blade Electric food Inner surface crusher BladeElectric meat Inner surface grinder for kitchen Blade use Electricblender for Inner surface kitchen use Blade Electric mixer for Innersurface kitchen use Blade Example of Preferred Applying Other substratepolymer* method similar product Metal (aluminum, galvanized steel {closeoversize brace} I, II {close oversize brace} Coating plate) Metal(aluminium, Rice gruel galvanized steel cooker, rice plate) {closeoversize brace} I, II {close oversize brace} Coating warmer Metal MetalMetal Cooking utensils SUS, aluminum Cooking utensils SUS, aluminum (forslicing) Resin, wood Cooking utensils SUS, resin Cooking appli- SUS,resin {close oversize brace} I, II, III {close oversize brace} Coatingances and utensils SUS Cooking appli- SUS ances (food) Metal Electriccooking Metal appliances Metal Cooking iron Cooking appli- ances andfacil- ities Barbecue utensils Food processing machine and utensils(with press machine) Metal Cooking appli- Metal ances for mixing, Metalvegetable slicer, Metal, glass food slicer, Metal peeler, cutter forMetal, glass {close oversize brace} I, II, III {close oversize brace}Coating cutting into small Metal cubes, food cut- Metal, glass ter, meatchopper, Metal meat slicer, meat Metal, glass tenderizer, cutter Metalmixer, mixer, food mixer, blender, apple processor, continuous eggopening machine, soy bean curd cutter, food molder, bread crumb coatingmachine, veget- able washing machine

[0272] TABLE 5 Classifi- Typical cation of finished product productSimilar product Application Gas oven Gas oven Top plate, side plate,with grill outer surface Gas container built- Top plate, side plate, intype gas oven outer surface Hood for drip pan Outer surface of gas oven(made of metal) Range with Oven Inner surface (metallic oven (toast-(kitchen portion), pan for er, range) range) range, Inner surface ofdoor Oven for shop use Inner surface (metallic portion), pan for range,Inner surface of door Electric oven Inner surface (metallic portion),pan for range, Inner surface of door Electric oven Inner surface(metallic (with heating portion), pan for cabinet for shop range, use)Inner surface of door Electric oven (for Inner surface (metallic shopuse) portion), pan for range, Inner surface of door Oven for shop useInner surface (metallic portion), pan for range, Inner surface of doorCooking oven for Inner surface (metallic shop use portion), pan forrange, Inner surface of door Cooking range for Inner surface (metallicshop use portion), pan for range, Inner surface of door Oven for Innersurface (metallic baking bread portion), pan for range, Inner surface ofdoor Oven for baking Inner surface (metallic bread for shop useportion), pan for range, Inner surface of door Bread baker Inner surface(metallic (automatic, for portion), pan for domestic use) range, Innersurface of door Example of Preferred Applying substrate polymer* methodOther similar product Metal Portable range, oven with Metal {closeoversize brace} I, II {close oversize brace} Coating grill, portableelectric Metal range, gas range, gas oven with grill electric oven withgrill Metal Gas salamander, Metal, glass electric salamaner, Metalconvection oven Metal, glass Metal Metal, glass Metal Metal, glass Metal{close oversize brace} I, II {close oversize brace} Coating Metal, glassMetal Metal, glass Metal Metal, glass Metal Metal, glass Metal Oven forbaking bread Metal, glass Metal Metal, glass {close oversize brace} I,II {close oversize brace} Coating Metal Metal, glass

[0273] TABLE 6 Classifi- Typical cation of finished product productSimilar product Application Range with Electric oven Inner surface(metallic oven (toast- and toaster portion), pan for er, range) range,Inner surface of door Toaster Inner surface (metallic portion), pan forrange, Inner surface of door Toaster for bread Inner surface (metallicportion), pan for range, Inner surface of door Microwave Inner surface(metallic oven portion), pan for range, Inner surface of door Microwaverange Inner surface (metallic for shop use portion), pan for range,range, Inner surface of door Microwave range Inner surface (metallicwith oven portion), pan for range, Inner surface of door Rice cookerInner surface (for microwave range) Pan and pot Glass pot Inner surface,lid Enamel pot Inner surface, lid Aluminum pot Inner surface, lidElectric Inner surface of pot, lid frying pot Inner surface of pot, lidElectric Tempura Inner surface of pot, lid frying pot Inner surface ofpot, lid Electric Inner surface of pot, lid pressure pot Inner surfaceof pot, lid Electric Inner surface of pot, lid pressure pot Innersurface of pot, lid for stew Example of Preferred Applying substratepolymer* method Other similar product Metal Metal, glass Metal Metal,glass {close oversize brace} I, II {close oversize brace} Coating MetalMetal, glass Metal Metal, glass Metal Metal, glass {close oversizebrace} I, II {close oversize brace} Coating Metal Metal, glass MetalGlass Wok set for Chinese dishes, one-handed pot, double-handed potMetal {close oversize brace} I, II {close oversize brace} Coating Gasfryer, electromagnet-    Glass ic fryer, Tempura fryer, Metal oil filterunit    Glass Metal Buckwheat boiling pot, {close oversize brace} I, II{close oversize brace} Coating rotary pot    Glass Metal {close oversizebrace} I, II {close oversize brace} Coating    Glass

[0274] TABLE 7 Classifi- Typical cation of finished product productSimilar product Application Other Griddle Heating surface heating Lidappliance Electro- Cooking surface for cooking magnetic ElectromagneticCooking surface cooking range and oven appliance Electric Inner surfacecooking Inner surface of door steamer Food steamer for Inner surfaceshop use Lid Noodle Inner surface boiling Lid apparatus for shop useCooking Inner surface roaster for Inner surface of door shop use Cookingroaster for Inner surface (metallic shop use portion), pan for rangeTablewares Inner surface and cans washing machine for shop use HeatingInner surface cabinet for Inner surface of door shop use Garbage GarbageInner surface disposer disposer Garbage disposer Inner surface (wastes),garbage Inner surface disposer for house- Inner surface hould use,garbage disposer for making compost Example of Preferred Applyingsubstrate polymer* method Other similar product Metal Electric cookinggriddle Metal, glass {close oversize brace} I, II {close oversize brace}Coating for fried dumpling stuffed with minced pork MetalElectromagnetic range {close oversize brace} I, II {close oversizebrace} Coating Metal Metal Gas cooking steamer, Metal electric cookingsteamer Metal {close oversize brace} I, II {close oversize brace}Coating Metal, glass Metal {close oversize brace} I, II {close oversizebrace} Coating Metal, glass Metal glass {close oversize brace} I, II{close oversize brace} Coating Metal Metal } I, II, III } Coating Metal,glass } I, II, III } Coating Thawing box, food warmer, soup kettle,coffee maker, tea server, juice dispenser, miso soup dispenser, Sakewarmer Metal Metal Metal {close oversize brace} I, II, III {closeoversize brace} Coating Metal, glass

EXAMPLE Preparation Example 1

[0275] (Preparation of Aqueous Dispersion Comprising PFA HavingHydroxyl)

[0276] A 3-liter glass-lined autoclave equipped with a stirrer, valve,pressure gauge and thermometer was charged with 1,500 ml of pure waterand 9.0 g of ammonium perfluorooctanoate. After replacing with nitrogengas sufficiently, the autoclave was evacuated and charged with 20 ml ofethane gas.

[0277] Then 3.8 g ofperfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol)(formula (7)):

[0278] and 18 g of perfluoro(propyl vinyl ether) (PPVE) were fed intothe autoclave with pressurized nitrogen, and a temperature inside thesystem was maintained at 70° C.

[0279] Pressurized tetrafluoroethylene (TFE) gas was introduced into theautoclave with stirring so that the inside pressure of the autoclavebecame 8.5 kgf/cm²G.

[0280] Then a solution prepared by dissolving 0.15 g of ammoniumpersulfate in 5.0 g of water was added with pressurized nitrogen gas toinitiate the reaction.

[0281] Since the pressure lowered with the advance of the polymerizationreaction, it was increased again to 8.5 kgf/cm²G by feedingtetrafluoroethylene gas at the time when it lowered to 7.5 kgf/cm²G.Thus the decreasing and increasing of the pressure was repeated.

[0282] With continuing supply of tetrafluoroethylene, every time whenabout 40 g of tetrafluoroethylene gas was consumed after starting of thepolymerization, 1.9 g of the above-mentioned fluorine-containingethylenic monomer having hydroxyl (compound represented by the formula(7)) was introduced under pressure three times (5.7 g in total) tocontinue the polymerization. At the time when about 160 g oftetrafluoroethylene gas was consumed after starting of thepolymerization, the supplying thereof was terminated and the autoclavewas cooled and the un-reacted monomer was released to give 1,702 g of abluish semi-transparent aqueous dispersion.

[0283] A concentration of the polymer in the obtained aqueous dispersionwas 10.9%, and a particle size measured by dynamic light scatteringmethod was 70.7 nm.

[0284] Also a part of the obtained aqueous dispersion was sampled andsubjected to freeze coagulation, and the precipitated polymer was rinsedand dried to isolate a white solid. Components and their amounts of theobtained copolymer which were determined through ¹⁹F-NMR and IR analyseswere TFE/PPVE/(Fluorine-containing ethylenic monomer having hydroxyl andrepresented by the formula (7))=97.7/1.2/1.1% by mole.

[0285] In infrared spectrum, characteristic absorption of —OH wasobserved at 3,620 to 3,400 cm⁻¹.

[0286] According to DSC analysis, Tm was 310° C., and according to DTGAanalysis, 1% thermal decomposition temperature Td was 368° C. A meltflow rate measured under conditions of preheating at 372° C. for fiveminutes at a load of 7 kgf/cm² by using Koka-type flow tester andnozzles of 2 mm×8 mm length was 12.0 g/10 min.

Preparation Example 2

[0287] (Preparation of Aqueous Dispersion Comprising PFA HavingHydroxyl)

[0288] The same autoclave as in Preparation Example 1 was charged with1,500 ml of pure water and 9.0 g of ammonium perfluorooctanoate. Afterreplacing with nitrogen gas sufficiently, the autoclave was evacuatedand charged with 20 ml of ethane gas.

[0289] Then 1.9 g ofperfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol)(compound of the formula (7)) and 16.1 g of perfluoro(propyl vinylether) (PPVE) were fed into the autoclave with pressurized nitrogen gas,and a temperature inside the system was maintained at 70° C.

[0290] Pressurized tetrafluoroethylene (TFE) gas was introduced into theautoclave with stirring so that the inside pressure became 8.5 kgf/cm²G.

[0291] Then a solution prepared by dissolving 0.15 g of ammoniumpersulfate in 5.0 g of water was fed with pressurized nitrogen gas toinitiate the reaction.

[0292] Since the pressure lowered with the advance of the polymerizationreaction, at the time when the pressure lowered down to 7.5 kgf/cm²G, itwas increased again to 8.5 kgf/cm²G with tetrafluoroethylene gas, andthe decreasing and increasing of the pressure were repeated.

[0293] With continuing supply of tetrafluoroethylene, every time when 40g of tetrafluoroethylene gas was consumed after starting of thepolymerization, 0.95 g of the fluorine-containing ethylenic monomerhaving hydroxyl (compound represented by the formula (7)) was introducedthree times (2.85 g in total) under pressure to continue thepolymerization. When 160 g of tetrafluoroethylene was consumed afterstarting of the polymerization, the supplying thereof was terminated.The autoclave was cooled and the un-reacted monomer was released to give1,692 g of an aqueous dispersion. A concentration of the polymer in theobtained aqueous dispersion was 10.6% and a particle size thereof was76.8 nm.

[0294] A part of the aqueous dispersion was sampled, and a white solidwas isolated in the same manner as in Preparation Example 1.

[0295] Analysis of the obtained white solid indicates:

[0296] TFE/PPVE/(Fluorine-containing monomer having hydroxyl andrepresented by the formula (7))=98.3/1.1/0.6% by mole

[0297] Tm=310° C.

[0298] 1% Thermal decomposition temperature Td=374° C.

[0299] Melt flow rate: 9.5 g/10 min

[0300] In infrared spectrum, characteristic absorption of —OH wasobserved at 3,620 to 3,400 cm⁻¹.

Preparation Example 3

[0301] (Synthesis of Aqueous Dispersion of PFA Having no FunctionalGroup)

[0302] Emulsion polymerization was carried out in the same manner as inPreparation Example 1 except thatperfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol)(compound of the formula (7)) was not used, and 1,662 g of an aqueousdispersion of PFA having no functional group was obtained.

[0303] A concentration of the polymer in the aqueous dispersion was9.7%, and a particle size thereof was 115 nm.

[0304] A white solid was isolated and analyzed in the same manner as inPreparation Example 1.

[0305] TFE/PPVE=98.9/1.1% by mole

[0306] Tm=310° C.

[0307] 1% Thermal decomposition temperature Td=479° C.

[0308] Melt flow rate: 19.2 g/10 min

[0309] In infrared spectrum, no characteristic absorption of —OH wasobserved.

Preparation Example 4

[0310] (Synthesis of PFA Having Hydroxyl)

[0311] A 6-liter glass-lined autoclave equipped with a stirrer, valve,pressure gauge and thermometer was charged with 1,500 ml of pure water.After replacing with nitrogen gas sufficiently, the autoclave wasevacuated and charged with 1,500 g of1,2-dichloro-1,1,2,2-tetrafluoroethane (R-114).

[0312] Then 5.0 g ofperfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol)(compound of the formula (7)), 130 g of perfluoro(propyl vinyl ether)(PPVE) and 180 g of methanol were fed into the autoclave withpressurized nitrogen gas, and a temperature inside the system wasmaintained at 35° C.

[0313] Pressurized tetrafluoroethylene (TFE) gas was introduced into theautoclave with stirring so that the inside pressure became 8.0 kgf/cm²G. Then 0.5 g of a 50% methanol solution of di-n-propyl peroxydicarbonatewas fed with pressurized nitrogen to initiate the reaction.

[0314] Since the pressure lowered with the advance of the polymerizationreaction, at the time when the pressure lowered down to 7.5 kgf/cm²G, itwas increased again to 8.0 kgf/cm²G, and the decreasing and increasingof the pressure were repeated.

[0315] With continuing supply of tetrafluoroethylene, every time whenabout 60 g of tetrafluoroethylene gas was consumed after starting of thepolymerization, 2.5 g of the fluorine-containing ethylenic monomerhaving hydroxyl (compound represented by the formula (7)) was introducednine times (22.5 g in total) under pressure to continue thepolymerization. When about 600 g of tetrafluoroethylene was consumedafter starting of the polymerization, the supplying thereof wasterminated. The autoclave was cooled and the un-reacted monomer andR-114 were released.

[0316] The obtained copolymer was washed with water, rinsed withmethanol and then vacuum-dried to give 710 g of a white solid. Thecomposition of the obtained copolymer was TFE/PPVE/(Fluorine-containingethylenic monomer having hydroxyl and represented by the formula(7))=97.0/2.0/1.0% by mole according to ¹⁹F-NMR and IR analyses. Ininfrared spectrum, characteristic absorption of —OH was 1 observed at3,620 to 3,400 cm⁻¹. According to DSC analysis, Tm was 305° C., andaccording to DTGA analysis, 1% thermal decomposition temperature Td was375° C. A melt flow rate measured under conditions of preheating at 372°C. for five minutes at a load of 7 kgf/cm² by using Koka-type flowtester and nozzles of 2 mm diameter×8 mm length was 32 g/10 min.

Preparation Example 5

[0317] (Synthesis of PFA Having Hydroxyl)

[0318] A 6-liter glass-lined autoclave equipped with a stirrer, valve,pressure gauge and thermometer was charged with 1,500 ml of pure water.After replacing with nitrogen gas sufficiently, the autoclave wasevacuated and charged with 1,500 g of1,2-dichloro-1,1,2,2-tetrafluoroethane (R-114).

[0319] Then the reaction was initiated in the same manner as inPreparation Example 4 except that 2.5 g ofperfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol),132 g of perfluoro(propyl vinyl ether) (PPVE) and 230 g of methanol wereused. A temperature inside the system was maintained at 35° C.

[0320] Pressurized tetrafluoroethylene (TFE) gas was introduced into theautoclave with stirring so that the inside pressure of the autoclavebecame 8.0 kgf/cm²G. Then 0.5 g of a 50% methanol solution ofdi-n-propyl peroxydicarbonate was added with pressurized nitrogen gas toinitiate the reaction.

[0321] Since the pressure lowered with the advance of the polymerizationreaction, it was increased again to 8.0 kgf/cm²G by feedingtetrafluoroethylene gas at the time when it lowered to 7.5 kgf/cm²G.Thus the decreasing and increasing of the pressure was repeated.

[0322] Further 680 g of a white solid copolymer was obtained in the samemanner as in Preparation Example 4 except that every time when about 60g of tetrafluoroethylene gas was consumed after starting of thepolymerization, 1.23 g of the above-mentioned fluorine-containingethylenic monomer having hydroxyl (compound represented by the formula(7)) was introduced under pressure nine times (11.10 g in total).Components and their amounts of the obtained copolymer which weredetermined through ¹⁹F-NMR and IR analyses wereTFE/PPVE/(Fluorine-containing ethylenic monomer having hydroxyl andrepresented by the formula (7))=97.6/2.0/0.4% by mole. In infraredspectrum, characteristic absorption of -OH was observed at 3,620 to3,400 cm⁻¹. According to DSC analysis, Tm was 310° C., and according toDTGA analysis, a decomposition starting temperature was 368° C. and 1%thermal decomposition temperature Td was 375° C. A melt flow ratemeasured under conditions of preheating at 372° C. for five minutes at aload of 7 kgf/cm² by using Koka-type flow tester and nozzles of 2 mmdiameter×8 mm length was 42 g/10 min.

Preparation Example 6

[0323] (Synthesis of PFA Having no Functional Group)

[0324] Synthesis was carried out in the same manner as in PreparationExample 4 except thatperfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol)(compound of the formula (7)) was not used and 240 g of methanol wasused, and 597 g of PFA having no functional group was obtained.

[0325] The obtained PFA was analyzed in the same manner as inPreparation Example 4 and the results were as follows.

[0326] TFE/PPVE=98.2/1.8% by mole

[0327] Tm=310° C.

[0328] Td=469° C. (1% weight reduction)

[0329] Melt flow rate: 24 g/10 min

Preparation Example 7

[0330] (Preparation of PFA Powder Coating Composition Having Hydroxyl)

[0331] The PFA powder having hydroxyl and prepared in PreparationExample 4 (apparent specific gravity: 0.5, true specific gravity: 2.1,average particle size: 600 μm) was compressed into a sheet of 60 mmwide×5 mm thick by a Roller Compactor (Model BCS-25 available fromShinto Kogyo Kabushiki Kaisha), and then crushed into about 10 mmdiameter by a crusher and further finely pulverized at room temperatureat 11,000 rpm by a pulverizer (Cosmomizer Model N-1 available from NaraKikai Seisakusho). Subsequently the coarse powder particles of not lessthan 170 mesh (88 μm of sieve opening) were separated by a classifier(Hibolder Model 300SD available from Shi-Tokyo Kikai Kabushiki Kaisha)to give a PFA powder coating composition having hydroxyl. An apparentdensity of the powder was 0.7 g/ml, and an average particle size thereofwas 20 μm.

Preparation Example 8

[0332] (Preparation of PFA Powder Coating Composition Having noFunctional Group)

[0333] A PFA powder coating composition was prepared in the same manneras in Preparation Example 7 except that the PFA powder having nofunctional group and prepared in Preparation Example 6 (apparentspecific gravity: 0.6, true specific gravity: 2.1, average particlesize: 400 μm) was used instead of the PFA powder having hydroxyl andprepared in Preparation Example 4. An apparent density of the obtainedpowder was 0.73 g/ml, and an average particle size thereof was 20 μm.

Preparation Example 9

[0334] (Synthesis of Fluorine-Containing Polymer Prepared by Using aNon-Fluorine-Containing Monomer Having Functional Group)

[0335] A 1-liter stainless steel autoclave equipped with a stirrer,valve, pressure gauge and thermometer was charged with 250 g of butylacetate, 36.4 g of vinyl pivalate (VPi) and as a non-fluorine-containingmonomer having hydroxyl, 32.5 g of 4-hydroxybutyl vinyl ether (HBVE) and4.0 g of isopropoxycarbonyl peroxide. After cooling to 0° C. with iceand replacing with nitrogen gas sufficiently, the autoclave wasevacuated and charged with 47.5 g of isobutylene (IB) and 142 g oftetrafluoroethylene (TFE).

[0336] The autoclave was heated to 40° C. and reaction was carried outfor 30 hours with stirring. At the time when the inside pressure of thereaction vessel is lowered to not more than 2.0 kg/cm², the reaction wasterminated. The autoclave was cooled and un-reacted gas monomer wasreleased, and thus a butyl acetate solution of a fluorine-containingpolymer was obtained. A polymer concentration was 45%.

[0337] A fluorine-containing polymer was separated from the obtainedbutyl acetate solution of fluorine-containing polymer throughre-precipitation method, followed by sufficiently reducing pressure anddrying, thus being separated in the form of white solid. According to¹H-NMR and ¹⁹F-NMR elementary analyses, the obtained fluorine-containingpolymer was a copolymer of TFE/IB/VPi/HBVE=44/34/15/7% by mole.

Preparation Example 10

[0338] (Production of Film of PFA Having Hydroxyl)

[0339] A metal die of 100 mm diameter was charged with 8.0 g of thewhite solid obtained in Preparation Example 4 and set on a press machineof 350° C., followed by preheating for 30 minutes and thencompression-molding at 70 kg/cm² for one minute. Thus a 0.5 mm thickfilm was obtained.

Preparation Example 11

[0340] (Production of Film of PFA Having Hydroxyl)

[0341] The same procedures as in Preparation Example 10 were repeatedexcept that the white solid obtained in Preparation Example 5 was used,to give a 0.5 mm thick film.

Preparation Example 12

[0342] (Production of Film of PFA Having no Functional Group)

[0343] The same procedures as in Preparation Example 10 were repeatedexcept that the white solid obtained in Preparation Example 6 was used,to give a 0.5 mm thick film.

Preparation Example 13

[0344] (Production of Film of PFA Having Hydroxyl by Extrusion)

[0345] The white solid obtained in Preparation Example 4 was extruded at350° to 370° C. by using a biaxial extruder (LABOPLASTOMIL availablefrom Toyo Seiki Kabushiki Kaisha) to give pellets. The pellets wereextruded at 360° to 380° C. at a roll temperature of 120° C. by using auniaxial extruder (LABOPLASTOMIL available from Toyo Seiki KabushikiKaisha) to give a film of 10 cm wide×100 to 150 μm thick.

Preparation Example 14

[0346] (Production of Film of PFA Having no Functional Group byExtrusion)

[0347] The same procedures as in Preparation Example 13 were repeatedexcept that the white solid obtained in Preparation Example 6 was used,to give pellets. Further extrusion was carried out in the same manner asin Preparation Example 17 to give a film of 10 cm wide×100 to 150 μmthick.

Preparation Example 15

[0348] (Production of Laminated Film of PFA Having Hydroxyl and PTFE)

[0349] The film of PFA having hydroxyl and obtained in PreparationExample 13 and a 0.5 mm thick PTFE film were overlapped andcompression-molded in the same manner as in Preparation Example 10.

[0350] The two layers were adhered strongly.

Example 1

[0351] (1) Pre-Treatment of Substrate

[0352] A 1.5 mm thick pure aluminum plate (A1050P) and a 1.5 mm thickSUS304 plate were degreased respectively with acetone.

[0353] (2) Formation of Primer Layer Comprising Fluorine-ContainingPolymer Having Functional Group

[0354] An aqueous dispersion comprising PFA having hydroxyl and preparedin Preparation Example 1 was applied to the plate by an air spray sothat a coating thickness would become about 5 μm, followed byinfrared-drying at 90° C. for 10 minutes and sintering at 380° C. for 20minutes.

[0355] (3) Formation of Layer (Top Layer) Comprising Fluorine-ContainingPolymer Having no Functional Group

[0356] Onto the primer layer obtained in (2) above was applied anaqueous coating composition of PTFE (POLYFLON TFE Enamel EK4300CRNavailable from DAIKIN INDUSTRIES, LTD.) as a coating composition offluorine-containing polymer having no functional group by an air sprayso that a coating thickness would become about 20 μm, followed byinfrared-drying at 90° C. for 10 minutes and sintering at 380° C. for 20minutes.

[0357] (4) Evaluation of Adhesive Property

[0358] The method of evaluation is as follows.

[0359] (Cross-Cut Adhesion Test)

[0360] According to JIS K 5400 1990, 8. 5. 2, a coated surface wascross-cut to give 100 squares, and an adhesive tape (available fromNichiban Kabushiki Kaisha) is adhered to the cross-cut surfacesufficiently. Then immediately the tape is torn off. This is repeated 10times with new adhesive tapes to check to see how many squares remainamong 100 squares. The results are shown in Table 8.

Example 2

[0361] A coated plate was produced in the same manner as in Example 1except that a primer layer was formed by using the aqueous dispersioncomprising PFA having hydroxyl and obtained in Preparation Example 2 asa primer comprising a fluorine-containing polymer having functionalgroup. The evaluation for adhesive property was carried out, and theresults are shown in Table 8.

Comparative Example 1

[0362] A coated plate was produced in the same manner as in Example 1except that a primer layer was formed by using the aqueous dispersioncomprising PFA having no functional group and obtained in PreparationExample 3 instead of a primer comprising a fluorine-containing polymerhaving functional group. The evaluation for adhesive property wascarried out, and the results are shown in Table 8.

Examples 3 and 4 and Comparative Example 2

[0363] Coated plates were produced in the same manner as in Example 1 incase of Example 3, in Example 2 in case of Example 4 and in ComparativeExample 1 in case of Comparative Example 2 except that a top layer wasformed by using an aqueous coating composition comprising FEP (NEOFLONFEP Dispersion ND-1 available from DAIKIN INDUSTRIES, LTD) as a coatingcomposition comprising a fluorine-containing polymer having nofunctional group. The evaluation for adhesive property was carried out,and the results are shown in Table 8.

Example 5

[0364] (1) Pre-Treatment of Substrate

[0365] Pre-treatment was carried out in the same manner as in Example 1.

[0366] (2) Formation of Primer Layer Comprising Fluorine-ContainingPolymer Having Functional Group

[0367] An aqueous dispersion comprising PFA having hydroxyl and preparedin Preparation Example 1 was applied to the plate by an air spray sothat a coating thickness would become about 5 μm, followed byinfrared-drying at 90° C. for 10 minutes.

[0368] (3) Formation of Layer (Top Layer) Comprising Fluorine-ContainingPolymer Having no Functional Group

[0369] Onto the primer layer obtained in (2) above was applied a powdercoating composition of PFA (NEOFLON PFA Powder Coating CompositionACX-31 available from DAIKIN INDUSTRIES, LTD.) as a coating compositionof fluorine-containing polymer having no functional group byelectrostatic coating so that a coating thickness would become 40 μm,followed by sintering at 380° C. for 20 minutes.

[0370] (4) Evaluation of Adhesive Property

[0371] The evaluation was carried out in the same manner as in Example1, and the results are shown in Table 8.

Example 6

[0372] A coated plate was produced in the same manner as in Example 5except that a primer layer was formed by using the aqueous dispersioncomprising PFA having hydroxyl and obtained in Preparation Example 2 asa primer comprising a fluorine-containing polymer having functionalgroup. The evaluation for adhesive property was carried out, and theresults are shown in Table 8.

Comparative Example 3

[0373] A coated plate was produced in the same manner as in Example 5except that a primer layer was formed by using the aqueous dispersioncomprising PFA having no functional group and obtained in PreparationExample 3 instead of a primer comprising a fluorine-containing polymerhaving functional group. The evaluation for adhesive property wascarried out, and the results are shown in Table 8.

Example 7

[0374] (Evaluation of Adhesive Property of PFA Powder CoatingComposition Having Hydroxyl)

[0375] (1) Production of Press Sheet for Adhesion Test

[0376] About 4 kg of the powder coating composition having hydroxyl andprepared in Preparation Example 7 was put in a cylindrical metal mold of60 mm diameter and compression-molded at room temperature at a pressureof 300 kgf/cm² with a press machine to give a disc-like cold press sheet(hereinafter also referred to as “PFA sheet”).

[0377] (2) Pre-Treatment of Substrate

[0378] A pure aluminum plate of 100×100×1 (mm) was degreased withacetone and then subjected to sand blasting.

[0379] (3) Production of Adhered Sample

[0380] The PFA sheet obtained in (1) above was placed on the aluminumplate ((2) above) and put in a hot air dryer to heat and melt at 330° C.for 10 minutes. Thus a sample produced by adhering the PFA sheet ofabout 450 μm thick to the aluminum plate was obtained. FIG. 1 shows adiagrammatic plan view of the adhered plate comprising the PFA sheet 1and the aluminum plate 2.

[0381] (4) Measurement of Adhesive Strength

[0382] As shown in FIG. 1, the PFA sheet 1 of the adhered sampleobtained in (3) above was cut with a cutter at intervals of a width a(10 mm) and one end of strip-like sheet 1 was folded up, thus giving atest sample for measuring adhesive strength. FIG. 2 shows a diagrammaticperspective view of the test sample for measuring adhesive strength. Asshown in FIG. 2, the sheet 1 was pulled up at an angle of 90° to thealuminum plate 2 to measure adhesive strength. The adhesive strength wasmeasured at room temperature at a cross head speed of 50 mm/min withTENSILON Universal Tester (available from Orientec Corporation). Anadhesive strength was 5.5 kgf/cm as an average value of peel by areamethod.

Comparative Example 4

[0383] (Evaluation of Adhesive Property of PFA Powder CoatingComposition Having no Functional Group)

[0384] Production of a press sheet for adhesion test, pre-treatment of asubstrate and production of an adhered sample were carried out in thesame manner as in Example 7 except that the powder coating compositionof PFA having no functional group and prepared in Preparation Example 8was used instead of the powder coating composition of PFA havinghydroxyl and prepared in Preparation Example 7. Then adhesive strengthwas measured.

[0385] Adhesive strength of the powder coating composition of PFA havingno functional group was 0.8 kgf/cm.

Example 8

[0386] (Electrostatic Coating of PFA Powder Coating Composition HavingHydroxyl)

[0387] Electrostatic coating of the PFA powder coating compositionhaving hydroxyl and prepared in Preparation Example 7 was carried out onan aluminum plate pre-treated in the same manner as in Example 7 at roomtemperature at a voltage of 40 kV with an electrostatic coating machine(Model GX3300 available from Iwata Toso Kabushiki Kaisha). The coatedplate was sintered at 330° C. for 15 minutes with a hot air dryer togive a coating film.

[0388] The coating film was a continuous uniform transparent film andwas adhered strongly to the aluminum plate.

Comparative Example 5

[0389] (Heat Resistance of Fluorine-Containing Polymer Prepared by UsingNon-Fluorine-Containing Monomer Having Functional Group)

[0390] Thermal decomposition temperature of the fluorine-containingpolymer prepared in Preparation Example 9 was measured through TGAanalysis, and 1% thermal decomposition temperature was 220° C. Therebyit is seen that heat resistance of the fluorine-containing polymerprepared by using a non-fluorine-containing monomer having functionalgroup like the polymer obtained in Preparation Example 9 is low.

[0391] Further the fluorine-containing copolymer obtained in PreparationExample 9 was dissolved in butyl acetate in a concentration of 10% byweight.

[0392] Pre-treatment of a pure aluminum substrate, application of aprimer layer comprising the fluorine-containing copolymer of PreparationExample 9 and application (electrostatic coating of PFA powder coatingcomposition) of a top layer were carried out in the same manner as inExample 5 except that for the primer layer, a butyl acetate solution ofthe fluorine-containing copolymer of Preparation Example 9 was usedinstead of the aqueous dispersion of PFA having hydroxyl.

[0393] A coating film obtained by sintering at 380° C. for 20 minutesafter the application was colored yellow-brown, and foaming and peelingwere also seen. Thus a uniform transparent coating film could not beobtained. TABLE 8 Com. Com. Com. Ex. 1 Ex. 2 Ex. 1 Ex. 3 Ex. 4 Ex. 2 Ex.5 Ex. 6 Ex. 3 Fluorine-containing Prep. Prep. Prep. Prep. Prep. Prep.Prep. Prep. Prep. aqueous dispersion Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3Ex. 1 Ex. 2 Ex. 3 used for primer layer Fluorine-containing PTFE PTFEPTFE FEP FEP FEP PFA PFA PFA resin forming top layer Evaluation ofadhesion (Cross-out adhesion test) SUS304 100/100 100/100 0/100 100/100100/100  0/100 100/100 100/100 20/100 Pure aluminum 100/100 100/1000/100 100/100 100/100 20/100 100/100 100/100 30/100

Examples 9 to 12

[0394] (Adhesion Test of PFA Film Having Hydroxyl to Metal)

[0395] Adhesion test of a PFA film having hydroxyl (Film of PreparationExample 10 or 11) to a metal plate was carried out in the mannermentioned below by using degreased chromate-treated aluminum, purealuminum and steel plates of 0.5 mm thick. The results are shown inTable 9.

[0396] (Production of Test Piece for Peeling Test)

[0397]FIG. 3 is a diagrammatic perspective view of a laminated articlemade to produce a test piece for peeling test. As shown in FIG. 3, thePFA film having hydroxyl and obtained in Preparation Examples 10 or 11as an adhesive layer 3 and a 0.1 mm thick spacer 4 (aluminum foil) wereput between the two metal plates 5 and then set on a press machine of350° C., followed by preheating (20 minutes) and then compressing at 50kg/cm² for one minute to give a laminated article of length b (150mm)×width c (70 mm).

[0398] A thickness of the respective adhesive layers 3 of the obtainedlaminated articles was 0.1 mm. Further the laminated article was cut toa width of 25 mm and the spacer portion is bent in the shape of T at apoint apart by a distance e (100 mm) from one end of the laminatedarticle to give a test piece for the peeling test. FIG. 4 is adiagrammatic perspective view of the obtained test piece for peelingtest. In FIG. 4, numeral 3 represents an adhesive layer and numeral 5represents metal plates.

[0399] (Peeling Test)

[0400] The peeling test was carried out at room temperature at a crosshead speed of 50 mm/min by using TENSILON Universal Tester availablefrom Orientec Corporation according to T-type peeling test method of JISK6854-1977. The results show the maximum peeling strength (kgf/25 mm)and minimum peeling strength (kgf/25 mm)

Comparative Examples 6 to 8

[0401] (Adhesion Test of PFA Film Having no Functional Group to Metal)

[0402] Production of test pieces and peeling test were carried out inthe same manner as in Example 9 except that the PFA films having nofunctional group and obtained in Preparation Example 12 were usedinstead of the PFA films having hydroxyl and obtained in PreparationExample 10 or 11. The results are shown in Table 9.

Examples 13 and 14

[0403] (Adhesion Test of Film of PFA Having Hydroxyl to Glass)

[0404] Adhesion test of PFA having hydroxyl to Pyrex glass plate of30×20×5 mm was carried out in the manner mentioned below.

[0405] Further hot water resistance test and methanol dipping test ofthe laminated article after the adhesion were carried out. The resultsare shown in Table 10.

[0406] (Production of Test Piece for Tensile Shear Test)

[0407]FIG. 5 is a diagrammatic perspective view of a test piece fortensile shear test. As shown in Table 5, the PFA film having hydroxyl asan adhesive layer 3 which was obtained in Preparation Example 10 or 11(length f of 10 m, width g of 20 mm, thickness h of 0.1 mm) was putbetween the Pyrex glass sheets 6 (length i of 30 m, width g of 20 mm,thickness j of 5 mm), and a load of 3 kg was applied, followed byallowing to stand at 350° C. for 30 minutes in an electric oven to givea test piece. A thickness of the adhesive layer 3 was adjusted to 0.1 mmwith a spacer.

[0408] (Adhesive Strength)

[0409]FIG. 6 is a diagrammatic perspective view of a test device to beused for measuring adhesive strength by tensile shearing method. Asshown in FIG. 6, the test piece 7 obtained as mentioned above and testjigs 8 matching the shape of the test piece were set on TENSILONUniversal Tester 9 available from Orientec Corporation, and then thetensile shearing test was carried out at a cross head speed of 20mm/min. The results of the measurement are shown by maximum adhesivestrength (kgf/cm²).

[0410] (Hot Water Resistance Test)

[0411] The test piece obtained as mentioned above was dipped in 50° C.hot water to check to see adhesion after a lapse of 6 hours and measureadhesive strength (kgf/cm²) after a lapse of 72 hours.

[0412] (Methanol Dipping Test)

[0413] The test piece obtained as mentioned above was dipped in methanolof room temperature to check to see adhesion.

Comparative Example 9

[0414] (Adhesion of Film of PFA Having no Functional Group to Glass)

[0415] Production of a test piece and various tests were carried out inthe same manner as in Example 13 except that the PFA film having nofunctional group and obtained in Preparation Example 12 was used insteadof the PFA film having hydroxyl and obtained in Preparation Example 10or 11. The results are shown in Table 10.

Example 15

[0416] (Tests for Adhesion and Post-Processability After Lamination ofPFA Film Having Hydroxyl to Stainless Steel)

[0417] A laminated test plate was produced in the manner mentioned belowby using a degreased SUS304 stainless steel plate of 150 mm long×70 mmwide×0.5 mm thick as a metal plate. The PFA film having hydroxyl andproduced in Preparation Example 13 and the PFA film having no functionalgroup and produced in Preparation Example 14 were cut to the same sizeas the above-mentioned SUS plate.

[0418] Further a polyimide film (Kapton 200-H available from E.I. DuPont) which was used as a film for separation was cut to the same sizeas above.

[0419]FIG. 7 is a diagrammatic cross-sectional view of a laminated testplate. As shown in FIG. 7, the PFA film 12 having hydroxyl, the PFA film13 having no functional group and the polyimide film 14 were put betweenthe two SUS plates 11, and then set on a press machine preset at 350°C., followed by preheating (20 minutes) and then pressing at 50 kg/cm²for one minute to give a laminated test plate.

[0420] After cooling, when the SUS plate 11 contacting the polyimidefilm 14 was removed, the polyimide film was peeled from the interfacewith the PFA film 13 having no functional group spontaneously.

[0421] As a result, a three-layered laminated article having goodtransparency and comprising the PFA film 12 having hydroxyl as anadhesive layer, the SUS plate 11 and the PFA film 13 having nofunctional group was obtained. FIG. 8 is a diagrammatic cross-sectionalview of the obtained three-layered laminated article.

[0422] Further the surface film of the obtained three-layered laminatedarticle was cross-cut with a cutting knife so that a cut depth reachedto the surface of the SUS plate 11, and a hundred pieces of 1 mm squaresof lattice pattern was made. A center of the square was pushed out by 5mm with Erichsen tester. As a result, the PFA film 12 having hydroxylwas not peeled off at all and kept adhered strongly to the SUS plate 11which was a substrate.

[0423] The PFA film 12 exhibited strong adhesion to the SUS plate 11.

Comparative Example 10

[0424] (Tests for Adhesion and Post-Processability After Lamination ofPFA Film Having no Functional Group to Stainless Steel)

[0425] A laminated article comprising the SUS plate 11 and the PFA film13 having no functional group was produced in the same manner as inExample 15 except that the PFA film having hydroxyl was not used. FIG. 9is a diagrammatic cross-sectional view of the obtained laminatedarticle.

[0426] The film seemed to be adhered, but the PFA film 13 having nofunctional group could be peeled off from the SUS sheet 11 easily.

[0427] Further Erichsen test was carried out in the same manner as inExample 15, and 60 pieces among 100 cross-cut squares were peeled offfrom the cut line.

Example 16

[0428] (Adhesion Test of PFA Film Having Hydroxyl and Polyimide Film)

[0429] The PFA film 12 having hydroxyl and obtained in PreparationExample 13, the PFA film 13 having no functional group and obtained inPreparation Example 14 and the polyimide film 14 were cut to the samesize as in Example 15, and put between the two SUS plates 11, followedby heating with a press machine in the same manner as in Example 15 togive a laminated test plate. FIG. 10 shows a diagrammaticcross-sectional view of the obtained laminated test plate. Then aftercooling, the SUS plate 11 was removed to obtain a laminated article.FIG. 11 is a diagrammatic cross-sectional view of the obtained laminatedarticle. Further the laminated article was cut to a width of 25 mm.

[0430] Subsequently FIG. 12 is a diagrammatic cross-sectional view ofthe above-mentioned laminated article to be subjected to T-type peelingtest. In FIG. 12, a part of interface between the polyimide film 14 andthe PFA film 12 having hydroxyl was peeled, and the T-type peeling testby peeling in the direction of an arrow shown in FIG. 12 was carried outin the same manner as in Example 1. The adhesive strength was 4.0 kgf/25mm as an average value of peel according to area method.

Comparative Example 11

[0431] (Adhesion Test of PFA Film Having no Functional Group andPolyimide Film)

[0432]FIG. 13 is a diagrammatic cross-sectional view of a laminatedarticle to be subjected to T-type peeling test in the same manner as inExample 1. In FIG. 13, a part of interface between the polyimide film 14and the PFA film 13 having no functional group of the 25 mm widelaminated article obtained in Example 16 was peeled, and the T-typepeeling test by peeling in the direction of an arrow shown in FIG. 13was carried out in the same manner as in Example 16, but no adhesiveproperty was exhibited.

Comparative Example 12

[0433] (Heat Resistance of Fluorine-Containing Polymer Prepared by UsingNon-Fluorine-Containing Monomer Having Functional Group)

[0434] A thermal decomposition temperature of the fluorine-containingpolymer obtained in Preparation Example 9 was measured through TGAanalysis, and 1% thermal decomposition temperature was 220° C. Fromthat, it is seen that the fluorine-containing polymer as prepared inPreparation Example 9 by using a non-fluorine-containing monomer havingfunctional group has low heat resistance.

[0435] Further the fluorine-containing polymer prepared in PreparationExample 9 was dissolved in butyl acetate in a concentration of 10% byweight.

[0436] To the aluminum plate pre-treated in the same manner as inExample 9 was applied the butyl acetate solution of fluorine-containingpolymer of Preparation Example 9 by an air spray so that a coatingthickness would become about 10 μm, followed by infrared-drying at 90°C. for 10 minutes.

[0437] On the coating film 16 of the fluorine-containing polymerprepared by using a non-fluorine-containing monomer having functionalgroup were placed in order the PFA film 13 having no functional groupand prepared in Preparation Example 14, the polyimide film 14 forseparation (same as in Example 15) and the aluminum plate 15, followedby heating and pressing at 350° C. with a press machine in the samemanner as in Example 15 to give a laminated test plate. A diagrammaticcross-sectional view of the obtained laminated test plate is shown inFIG. 14.

[0438] After cooling the laminated test plate, the aluminum plate 15contacting the polyimide film 14 and the polyimide film 14 were removedto give a laminated article.

[0439] The obtained laminated article was colored yellow-brown, andfoaming and peeling occurred between the PFA film 13 and the aluminumplate 15. Thus a uniform transparent laminated article could not beobtained. TABLE 9 Ex. 9 Ex. 10 Com. Ex. 6 Ex. 11 Com. Ex. 7 Ex. 12 Com.Ex. 8 Kind of fluorine- Prep. Ex. 10 Prep. Ex. 11 Prep. Ex. 12 Prep. Ex.10 Prep. Ex. 12 Prep. Ex. 10 Prep. Ex. 12 containing adhesive Kind ofmetal plate Chromate- Chromate- Chromate- Pure Pure Dull- Dull- treatedtreated treated aluminum aluminum finished finished aluminum aluminumaluminum steel sheet steel sheet Maximum peeling 15.4 11.3 1.8 9.5 1.522.4 2.0 strength (kgf/25 mm) Minimum peeling  7.2  2.1 0.18 2.5 0.1512.4 0.20 strength (kgf/25 mm)

[0440] TABLE 10 Ex. 13 Ex. 14 Com. Ex. 9 Kind of fluorine- Prep. Ex. 10Prep. Ex. 11 Prep. Ex. 12 containing adhesive Kind of substrate Pyrexglass Pyrex glass Pyrex glass Adhesive strength 83 or more 83 or more 59(kgf/cm²) Breaking of Breaking of Peeling glass glass Hot water Adhesionwas Adhesion was Spontaneous resistance (50° C.) maintained, maintained.peeing 6 hours after Adhesive strength 63 10 — (kgf/cm²) 72 hours afterMethanol dip test Adhesion was — Spontaneous (room temperature)maintained. peeing 24 hours 72 hours Adhesion was — — maintained.

Examples 17 and 18

[0441] Non-stickiness test was carried out through the method mentionedbelow by using, as a test plate, the plate electrostatically coated withthe PFA powder coating composition having hydroxyl of Example 8 (Example17) and the extruded film of PFA having hydroxyl of Preparation Example13 (Example 18). The results are shown in Table 11.

[0442] (Non-Stickiness Test)

[0443] Measurement was made at 23° C.±2° C. FIG. 15 is a diagrammaticperspective view of a test piece used for non-stickiness test. The testplate 17 has a length of not less than 150 mm and stains on the surfacethereof was wiped off with acetone. First, a 18 mm wide adhesive tape 18(JIS Z 1522) was cut to a length of 300 mm and only a 150 mm longportion k was put on the test plate 17. Then the tape 18 was scrubbedfor bonding by using an eraser of JIS S 6050 to obtain an adheredportion 19. To the remaining 150 mm long portion is adhered a paper (notillustrated) to make handling of the tape easy. After the bonding, thetape was allowed to stand for about 20 minutes so that the tape 18 wasfitted more to the test plate 17. The tape 18 was peeled up to a width mof 25 mm from the end of the test plate 17, and the test plate 17 wasmounted on a lower chuck device of a tension tester. The end of thepeeled tape 18 was folded by 180 degree, and was fitted to an upperchuck device so that the tape 18 was peeled straight. A force whichpeeled the tape 18 from the test plate 17 with the tester was measuredat a stretching speed of 20 mm/minute. The force was an average of thevalues measured when the tape 18 was peeled smooth. The results areshown in Table 11.

Comparative Examples 15 and 16

[0444] (Non-Stickiness Test of Film of PFA Having no Functional Group)

[0445] Non-stickiness test was carried out in the same manner as inExample 17 by using an extruded film of PFA having no functional groupand obtained in Preparation Example 14 (Comparative Example 15) andnon-coated glass plate (Comparative Example 16). The results are shownin Table 11. TABLE 11 Ex. 17 Ex. 18 Com. Ex. 15 Com. Ex. 16 Ex. 8 Prep.Ex. 13 Prep. Ex. 14 — Test sample Plate coated PFA film PFA film Glassplate with PFA having having no powder hydroxyl functional coating groupcomposition having hydroxyl Non-sticking 240 235 230 300 property (gf/18mm)

[0446] From Table 11, it was seen that PFA having OH group also has thesame excellent non-sticking property as PFA having no functional group.

Example 19

[0447] (Heat Resistance of Adhesion of Plate Coated with PFA PowderCoating Composition Having Hydroxyl)

[0448] (1) Production of Plate Coated with a Powder Coating Composition

[0449] An aluminum plate pre-treated in the same manner as in Example 7was coated with a powder coating composition of PFA having hydroxyl andprepared in Preparation Example 7 at room temperature at a voltage of 40kV by electrostatic coating by using an electrostatic powder coatingmachine (the same machine as in Example 8). The coated aluminum platewas sintered at 330° C. for 15 minutes to give a coating film. On theobtained coating film was applied a powder coating composition of PFAhaving no functional group (NEOFLON PFA Powder Coating CompositionACX-31 available from DAIKIN INDUSTRIES, LTD) by electrostatic coatingin the same manner as above, followed by sintering at 380° C. for 20minutes to give a transparent coating film having a total thickness of159 μm.

[0450] (2) Measurement of Adhesive Strength

[0451]FIG. 16 is a diagrammatic perspective view of an aluminum platehaving a coating film obtained in (1) of Example 19. As shown in FIG.16, the coating film 20 obtained in (1) above was cut with a cutter atintervals of a width n (10 mm) until the cutter reached the surface ofthe substrate, and one end of each cut strip of the coating film 20 waspeeled. Thus a coated sample was obtained for measuring adhesivestrength. FIG. 17 is a diagrammatic perspective view of the coatedsample for measuring adhesive strength.

[0452] As shown in FIG. 17, the coating film 20 was pulled up at anangle of 90 degrees to the aluminum plate 21 and peeling strength wasmeasured. The measurement was carried out at room temperature at a crosshead speed of 50 mm/min by using TENSILON Universal Tester (the same oneas in Example 7), and an average value of peel according to area methodwas assumed to be adhesive strength. The results are shown in Table 12.

[0453] (3) Measurement of Heat Resistance of Adhesion

[0454] A plate coated with a powder coating composition was producedseparately in the same manner as in above (1), and put in a hot airdryer set at 300° C. After the lapse of 200 hours and 500 hours, thecoated plate was taken out of the dryer. After the respective lapse oftime, the coated plate was cooled to room temperature, and test samplewas made and adhesive strength was measured in the same manner as in theabove (2). The results are shown in Table 12.

Comparative Example 17

[0455] (Heat Resistance of Adhesion of Plate Coated with Powder CoatingComposition and Having a Primer as an Adhesive Layer)

[0456] (1) Coating of Primer

[0457] An aluminum plate pre-treated in the same manner as in Example 7was coated with a heat resisting primer for a fluorine-containing resincoating composition (POLYFLON TFE Enamel EK1959DGN available from DAIKININDUSTRIES, LTD.) by spraying so that the coating thickness would becomeabout 10 μm, followed by sintering at 100° C. for 10 minutes.

[0458] (2) Production of Plate Coated with Powder Coating Composition

[0459] On the primer-coated plate of above (1) was applied only a PFApowder coating composition having no functional group (the same one asin Example 19) by electrostatic coating in the same manner as in (1) ofExample 19, followed by sintering at 380° C. for 20 minutes to give acoating thickness of 126 μm including the primer layer.

[0460] (3) Measurement of Adhesive Strength

[0461] The same procedures as in (2) of Example 19 were repeated. Theresults are shown in Table 12.

[0462] (4) Measurement of Heat Resistance of Adhesion

[0463] The same procedures as in (3) of Example 19 were repeated. Theresults are shown in Table 12.

Examples 20 and 21

[0464] (Heat Resistance of Adhesion of Plate Coated with PFA PowderCoating Composition Having Hydroxyl)

[0465] Plates coated with a powder coating composition were made andadhesive strength and heat resistance of adhesion were measured in thesame manner as in Example 19 except that instead of the aluminum plate,a SUS430 steel plate pre-treated like the aluminum plate (Example 20)and a galvanized steel plate subjected to only degreasing (Example 21)were used. The results are shown in Table 12.

Comparative Examples 18 and 19

[0466] (Heat Resistance of Adhesion of Plate Coated with Powder CoatingComposition and Having a Primer as an Adhesive Layer)

[0467] Plates coated with a powder coating composition were made andadhesive strength and heat resistance of adhesion were measured in thesame manner as in Comparative Example 17 except that instead of thealuminum plate, a SUS430 steel plate pre-treated like the aluminum plate(Comparative Example 18) and a galvanized steel plate subjected to onlydegreasing (Comparative Example 19) were used. The results are shown inTable 12. TABLE 12 Ex. 19 Ex. 20 Ex. 21 Com. Ex. 17 Com. Ex. 18 Com. Ex.19 Laminated article Appearance Transparent Transparent TransparentBrown Brown Brown coating film coating film coating film SubstrateAluminum SUS430 Galvanized steel Aluminum SUS430 Galvanized steel plateplate Surface layer Film of PFA Film of PFA Film of PFA Film of PFA Filmof PFA Film of PFA powder coating powder coating powder coating powdercoating powder coating powder coating composition compositioncomposition composition composition composition having no OH having noOH having no OH having no OH having no OH having no OH group 1) group 1)group 1) group 1) group 1) group 1) Adhesive layer Film of PFA Film ofPFA Film of PFA Primer for Primer for Primer for powder coating powdercoating powder coating fluorine-coating fluorine-coatingfluorine-coating composition composition composition resin coating 3)resin coating 3) resin coating 3) having OH having OH having OH group 2)group 2) group 2) Coating 140-180 110-140 150-170 120-140 100-120170-200 thickness (μm) Initial adhesive 1.7 1.6 not less than 2.0 2.02.0 0.9 strength (breakage of (kgf/cm) coating film) Heat resistance ofadhesion Adhesive not less than 1.2 not less than 1.5 0.95 0.1 0.7strength at 1.6 (breakage (breakage of 300° C. after of coating film)coating film) 200 hours (kgf/cm) Adhesive not less than 1.1 1.0 0.2 notmore than 0.1 0.4 strength at 1.6 (breakage 300° C. after of coatingfilm) 500 hours (kgf/cm)

Example 22

[0468] (Heat Resistance of Adhesion of Laminated Plate of PFA HavingHydroxyl)

[0469] (1) Production of Laminated Plate

[0470] An aluminum plate pre-treated in the same manner as in Example 7was used as a substrate. A PFA film having hydroxyl and obtained inPreparation Example 13 (thickness 100 μm), a PFA film having nofunctional group (NEOFLON PFA Film AF-0100 available from DAIKININDUSTRIES, LTD.) (thickness 100 μm) and a polyimide film for separation(the same one as in Example 15) were cut to the same size as thesubstrate.

[0471]FIG. 18 is a diagrammatic cross-sectional view of a laminated testplate. As shown in FIG. 18, the above-mentioned hydroxyl-containing PFAfilm 23, PFA film 24 having no functional group and polyimide film 25were inserted between the two aluminum plates 22 (one is a substrate),and set on a press machine preset at 350° C., followed by preheating(for 20 minutes) and then pressing at 50 kgf/cm² for one minute. Aftercooling, the polyimide film 25 and aluminum plate 22 contacting thepolyimide film 25 were removed to give a three-layered laminated articlecomprising the hydroxyl-containing PFA film 23 as an adhesive layer,aluminum plate 22 and PFA film 24. FIG. 19 is a diagrammaticcross-sectional view of the obtained three-layered laminated article.

[0472] (2) Adhesive Strength

[0473] A test sample for measuring adhesive strength was produced byusing the laminated plate (three-layered laminated article) obtained inabove (1) instead of the plate coated with a powder coating compositionand obtained in (1) of Example 19, and cutting at intervals of a widthof 10 mm in the same manner as in (2) of Example 19 and peeling one endof each strip-like film from an interface between the aluminum plate andthe hydroxyl-containing PFA film layer. The adhesive strength wasmeasured by pulling up the peeled film at an angle of 90 degrees in thesame manner as in (2) of Example 19. The results are shown in Table 13.

[0474] (3) Measurement of Heat Resistance of Adhesion

[0475] Another laminated plate of above (1) was produced separately, andmeasurement was made by using the produced laminated plate in the samemanner as in (3) of Example 19. The results are shown in Table 13.

Examples 23 and 24

[0476] (Heat Resistance of Adhesion of Hydroxyl-Containing PFA LaminatedPlate)

[0477] Production of laminated plates and measurements of adhesivestrength and heat resistance of adhesion were carried out in the samemanner as in Example 22 except that instead of the aluminum plate, aSUS430 steel plate surface-treated like the aluminum plate (Example 23)and a galvanized steel plate subjected to only degreasing (Example 24)were used. The results are shown in Table 13.

Comparative Example 20

[0478] (Heat Resistance of Adhesion of Laminated Plate Produced by UsingSurface-Treated Fluorine-Containing Resin Film)

[0479] (1) Surface-Treating of Fluorine-Containing Resin Film

[0480] One surface of a PFA film having no functional group (NEOFLON PFAFilm AF-0100 available from DAIKIN INDUSTRIES, LTD.) (thickness 100 μm)was surface-treated with TETRAETCH A (available from Kabushiki KaishaJyunkosha) by the method mentioned below. One surface of the PFA film(adhering surface) was wiped with acetone, and after drying, the wipedsurface was coated with a solution of TETRAETCH A. After the TETRAETCH Asolution was allowed to stand on the film for about 20 seconds, the filmwas washed with methanol and pure water and then dried. The treatedsurface turned brown. Further according to testing method of wettabilityof film described in JIS K-6768, wettability of the treated surface wasdetermined by using a standard test solution of 40 dyn/cm. It wasrecognized that the surface was uniformly wet and had been treatedsufficiently. Water contact angle of the treated surface was 61 degrees(110 degrees before treatment).

[0481] (2) Production of Laminated Plate

[0482] Two-liquid mixing type heat resisting epoxy adhesive (HITEMPHT-100L available from Kabushiki Kaisha Konishi) was coated on analuminum plate pretreated in the same manner as in Example 7. Thesurface-treated PFA film of above (1) was cut to the same size as thesubstrate, and its treated surface was brought into close contact to theadhesive layer of the substrate. After heating at 120° C. for one hour,sintering was carried out at 180° C. for 20 hours for curing andadhering the film to the substrate.

[0483] (3) Measurement of Adhesive Strength

[0484] A test sample for measuring adhesive strength was produced in thesame manner as in (2) of Example 22 by using the laminated plateobtained in above (2) instead of the laminated plate obtained in Example22, and cutting at intervals of a width of 10 mm and peeling one end ofeach strip-like film from an interface between the PFA film and theadhesive layer. The adhesive strength was measured in the same manner asin (2) of Example 19 by pulling up the peeled film at an angle of 90degrees to the substrate. The results are shown in Table 13.

[0485] (4) Measurement of Heat Resistance of Adhesion

[0486] Another laminated plate of above (2) was produced, and by usingit, measurement was made in the same manner as in (3) of Example 19. Theresults are shown in Table 13.

Comparative Example 21 and 22

[0487] (Heat Resistance of Adhesion of Laminated Article Produced byUsing Surface-Treated Fluorine-Containing Resin Film)

[0488] Surface-treating of a fluorine-containing resin film, productionof laminated plates and measurements of adhesive strength and heatresistance of adhesion were carried out in the same manner as inComparative Example 20 except that instead of the aluminum plate, aSUS430 steel plate surface-treated like the aluminum plate (ComparativeExample 21) and a galvanized steel plate subjected to only degreasing(Comparative Example 22) were used. The results are shown in Table 13.

Comparative Example 23

[0489] (Heat Resistance of Adhesion of Laminated Article Produced byUsing Surface-Treated Film)

[0490] (1) Surface Treatment of Fluorine-Containing Resin Film

[0491] A surface-treated FEP film (NEOFLON FEP Film NF-0100B1 availablefrom DAIKIN INDUSTRIES, LTD., one side is surface-treated) (thickness100 μm) was used instead of the PFA film of (1) of Comparative Example20 surface-treated with TETRAETCH.

[0492] (2) Production of Laminated Plate

[0493] An epoxy adhesive was coated on a pre-treated aluminum plate anda surface-treated film was laminated on the coated aluminum plate in thesame manner as in (2) of Comparative Example 20 except that thesurface-treated FEP film of above (1) was used instead of the PFA filmsurface-treated with TETRAETCH.

[0494] (3) Measurement of Adhesive Strength

[0495] Production of a test sample and measurement of adhesive strengthwere carried out in the same manner as in Comparative Example 20 exceptthat the laminated plate obtained in above (2) was used instead of thelaminated plate which was produced by using a PFA film treated withTETRAETCH in (2) of Comparative Example 20.

[0496] (4) Measurement of Heat Resistance of Adhesion

[0497] Another laminated plate of above (2) was produced, and by usingit, measurement was carried out in the same manner as in (3) of Example19. The results are shown in Table 13.

Comparative Example 24 and 25

[0498] (Heat Resistance of Adhesion of Laminated Plate Produced by UsingSurface-Treated Fluorine-Containing Resin Film)

[0499] Production of laminated plates, and measurements of adhesivestrength and heat resistance of adhesion were carried out in the samemanner as in Comparative Example 23 except that instead of the aluminumplate, a SUS430 steel plate surface-treated like the aluminum plate(Comparative Example 24) and a galvanized steel plate subjected to onlydegreasing (Comparative Example 25) were used. The results are shown inTable 13. TABLE 13 Ex. 22 Ex. 23 Ex. 24 Com. Ex. 20 Com. Ex. 21 Com. Ex.22 Com. Ex. 23 Com. Ex. 24 Com. Ex. 25 Laminated article AppearanceTransparent Transparent Transparent Brown Brown Brown Brown Brown Browncoating film coating film coating film Substrate Aluminum SUS430Galvanized Aluminum SUS430 Galvanized Aluminum SUS430 Galvanized steelplate steel plate steel plate Surface layer Film of PFA Film of PFA Filmof PFA PFA film PFA film PFA film Surface- Surface- Surface- having nohaving no having no surface-treated surface-treated surface-treatedtreated FEP treated FEP treated FEP OH group 1) OH group 1) OH group 1)with TETRA_ with TETRA- with TETRA- film 4) film 4) film 4) ETCH ETCHETCH Adhesive PFA film PFA film PFA film Heat resisting Heat resistingHeat resisting Heat resis- Heat resis- Heat resis- layer having OHhaving OH having OH epoxy adhesive epoxy adhesive epoxy adhesive tiveepoxy tive epoxy tive epoxy group 2) group 2) group 2) 3) 3) 3) adhesive3) adhesive 3) adhesive 3) Coating 180-220 170-200 200-230 150-190160-190 170-190 130-160 160-180 160-180 thickness (μm) Initial adhe- 2.12.5 2.2 1.6 1.0 1.6 1.5 1.5 1.5 sive strength (kgf/cm) Heat re- sistanceof adhesion Adhesive not less than 2.2 not less than SpontaneousSpontaneous Spontaneous Spontaneous Spontaneous Spontaneous strength at2.0 (break- 2.0 (break- peeling peeling peeling peeling peeling peeling300° C. after age of film) age of film) (peeling at (peeling at (peelingat (peeling at (peeling at (peeling at 500 hours substrate side)substrate side) substrate side) substrate substrate substrate (kgf/cm)side) side) side)

[0500] According to the present invention, it is possible to obtain acomposite material for cooking apparatuses which is produced byapplying, to a substrate, a material comprising a fluorine-containingpolymer having excellent adhesive property, without necessitatingcomplicated steps. Further according to the present invention, it ispossible to obtain a composite material for cooking apparatuses which isexcellent in heat resistance, non-sticking property, stain-proofingproperty, water- and oil-repelling property, stain removing property,chemical resistance, rust-preventive property, antibacterial property,resistance to energy ray and friction property.

1. Composite materials for cooking apparatuses produced by applying, toa substrate, a material comprising a fluorine-containing ethylenicpolymer having functional group and prepared by copolymerizing; (a) 0.05to 30% by mole of at least one of fluorine-containing ethylenic monomershaving at least one functional group selected from the group consistingof hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester groupand epoxy, and (b) 70 to 99.95% by mole of at least one offluorine-containing ethylenic monomers having no functional groupmentioned above.
 2. The composite materials for cooking apparatuses ofclaim 1, which are produced by applying, to a substrate, afluorine-containing ethylenic polymer having functional group, whereinsaid fluorine-containing ethylenic monomer (a) having functional groupis at least one of fluorine-containing ethylenic monomers havingfunctional group which are represented by the formula (1):CX₂═CX¹—R_(f)—Y  (1) wherein Y is —CH₂OH, —COOH, a carboxylic saltgroup, a carboxylic ester group or epoxy, X and X¹ are the same ordifferent and each is hydrogen atom or fluorine atom, R_(f) is adivalent fluorine-containing alkylene group having 1 to 40 carbon atoms,a fluorine-containing oxyalkylene group having 1 to 40 carbon atoms, afluorine-containing alkylene group having ether bond and 1 to 40 carbonatoms or a fluorine-containing oxyalkylene group having ether bond and 1to 40 carbon atoms.
 3. The composite materials for cooking apparatusesof claim 1 or 2, which are produced by applying, to a substrate, afluorine-containing ethylenic polymer having functional group, whereinthe fluorine-containing ethylenic monomer (b) having no functional groupis tetrafluoroethylene.
 4. The composite materials for cookingapparatuses of claim 1 or 2, which are produced by applying, to asubstrate, a fluorine-containing ethylenic polymer having functionalgroup, wherein the fluorine-containing ethylenic monomer (b) having nofunctional group is a monomer mixture of 85 to 99.7% by mole oftetrafluoroethylene and 0.3 to 15% by mole of a monomer represented bythe formula (2): CF₂═CF-R_(f) ¹  (2) wherein R_(f) ¹ is CF₃ or OR_(f) ²,in which R_(f) ² is a perfluoroalkyl group having 1 to 5 carbon atoms.5. The composite materials for cooking apparatuses of claim 1 or 2,which are produced by applying, to a substrate, a fluorine-containingethylenic polymer having functional group, wherein thefluorine-containing ethylenic monomer (b) having no functional group isa monomer mixture of 40 to 80% by mole of tetrafluoroethylene, 20 to 60%by mole of ethylene and 0 to 15% by mole of a monomer copolymerizabletherewith.
 6. The composite materials for cooking apparatuses of any ofclaims 1 to 5, which are produced by applying, to a substrate, thefluorine-containing ethylenic polymer having functional group in theform of a coating composition.
 7. The composite materials for cookingapparatuses of any of claims 1 to 4, which are produced by applying, toa substrate, the fluorine-containing ethylenic polymer having functionalgroup in the form of an aqueous dispersion.
 8. The composite materialsfor cooking apparatuses of any of claims 1 to 5, which are produced byapplying, to a substrate, the fluorine-containing ethylenic polymerhaving functional group in the form of a powder coating composition. 9.The composite materials for cooking apparatuses of any of claims 1 to 5,which are produced by applying, to a substrate, the fluorine-containingethylenic polymer having functional group in the form of a film.
 10. Thecomposite materials for cooking apparatuses of any of claims 1 to 5,wherein said substrate is a metallic substrate.
 11. The compositematerials for cooking apparatuses of any of claims 1 to 5, wherein saidsubstrate is a glass substrate. 12 Cooking apparatuses produced by usingthe composite materials for cooking apparatuses of claim 1 or
 2. 13.Heating apparatuses for cooking produced by using the compositematerials for cooking apparatuses of claim 1 or
 2. 14. A griddleproduced by using the composite materials for cooking apparatuses ofclaim 1 or
 2. 15. A griddle produced by using the composite materialsfor cooking apparatuses of claim 3 or 4 on its heating surface made ofmetal.
 16. A griddle produced by using the composite materials forcooking apparatuses of claim 4 or 5 on its glass lid.
 17. A range withoven produced by using the composite materials for cooking apparatusesof claim 1 or
 2. 18. A range with oven produced by using the compositematerials for cooking apparatuses of claim 3 or 4 on its inner surfacemade of metal.
 19. A range with oven produced by using the compositematerials for cooking apparatuses of claim 3 or 4 on its cooking plate.20. A range with oven produced by using the composite materials forcooking apparatuses of claim 4 on its glass door.
 21. A heating potproduced by using the composite materials for cooking apparatuses ofclaim 1 or
 2. 22. A heating pot produced by using the compositematerials for cooking apparatuses of claim 3 or 4 on its heating surfacemade of metal.
 23. A heating pot produced by using the compositematerials for cooking apparatuses of claim 4 or 5 on its glass lid. 24.A frying pan produced by using the composite materials for cookingapparatuses of claim 1 or
 2. 25. A frying pan produced by using thecomposite materials for cooking apparatuses of claim 3 or 4 on itsheating surface made of metal.
 26. A fryer produced by using thecomposite materials for cooking apparatuses of claim 1 or
 2. 27. A fryerproduced by using the composite materials for cooking apparatuses ofclaim 3 or 4 on its inner surface made of metal.
 28. A fryer produced byusing the composite materials for cooking apparatuses of claim 4 on itsinner surface made of glass.
 29. A rice cooker produced by using thecomposite materials for cooking apparatuses of claim 1 or
 2. 30. A ricecooker produced by using the composite materials for cooking apparatusesof claim 3 or 4 on its inner surface made of metal.
 31. A rice cookerproduced by using the composite materials for cooking apparatuses ofclaim 3 or 4 on its inner lid made of metal.
 32. A pot produced by usingthe composite materials for cooking apparatuses of claim 1 or
 2. 33. Apot produced by using the composite materials for cooking apparatuses ofclaim 3 or 4 on its inner surface made of metal.
 34. A pot produced byusing the composite materials for cooking apparatuses of claim 3 or 4 onits inner lid made of metal.
 35. A tableware or vessel produced by usingthe composite materials for cooking apparatuses of claim 1 or
 2. 36. Ametallic tableware or vessel produced by using the composite materialsfor cooking apparatuses of any of claims 3 to
 5. 37. A glass tablewareor vessel produced by using the composite materials for cookingapparatuses of claim 4 or
 5. 38. A cooking apparatus for processingfoods which is produced by using the composite materials for cookingapparatuses of claim 1 or
 2. 39. A cooking apparatus for mixing foodswhich is produced by using the composite materials for cookingapparatuses of claim 1 or
 2. 40. A cooking apparatus for cutting foodswhich is produced by using the composite materials for cookingapparatuses of claim 1 or
 2. 41. A baking apparatus produced by usingthe composite materials for cooking apparatuses of claim 1 or 2.